Is flu shot necessary?

According to the CDC, the flu vaccine reduces the odds of getting the flu by about 60%. But that number varies from year to year and among different groups of people.

You may wonder why there’s such a wide range. And in fact, it’s even wider than it seems: that statistic only applies to healthy adults. It turns out that the effectiveness of the flu vaccine depends on a number of different factors. Here’s a rundown of what they are.

Your Age

The flu vaccine doesn’t work equally well in all people. It’s most effective in healthy adults. In young children under 24 months, the flu vaccine is a little less effective at preventing the flu. It’s more effective as children get older.

After middle age, immunity naturally becomes weaker. The flu vaccine won’t work as well as it once did. But because the flu virus is much more dangerous for older people, it’s crucial that they get the vaccine. Even in cases where it doesn’t prevent the flu, it can still reduce the risk of serious side effects. Studies show that in older people who do not live in a care facility, the flu vaccine can cut the risk of hospitalization (for flu and pneumonia) by 30% to 70%. In people who do live in a nursing home or care facility, the flu vaccine is 50% to 60% effective in preventing hospitalization and 80% effective in preventing death from a flu complication.

There may also be slight differences depending on which vaccine you get.

This season, the American Academy of Pediatricians recommends that pediatricians offer flu shot to all children ages 6 months and older. The shot has provided the most consistent protection against the flu virus in recent years. Along with the CDC, the AAP supports the use of the nasal spray vaccine for children ages 2 and older for the 2018-19 season, but the spray’s effectiveness against the A/H1N1 strain of virus is an unknown.

A high-dose vaccine called Fluzone is recommended for adults age 65 and older when available. The high-dose flu shot contains four times as much active ingredient as a regular flu shot tp provide better immunity.

It’s that time again. Flu season is upon us, and everywhere we turn — from the family doctor’s office to the nightly news — we are reminded to get our flu shot.

It couldn’t be easier: You can get an influenza vaccine at your favorite neighborhood pharmacy, right along with your toothpaste and shampoo, or at a makeshift stand at the grocery store. At more and more businesses, employees can get one just down the hall from their desks.

During the 2010–2011 influenza season, about half of all children and 41 percent of American adults received flu shots. And health officials are pushing for more. The Centers for Disease Control and Prevention (CDC) “recommends that everyone 6 months of age and older get the annual flu vaccine,” says Joseph Bresee, MD, chief of the Epidemiology Prevention Branch at the CDC’s Influenza Division.

Not all experts agree with this advice, though. An increasing number of researchers, academics and doctors are questioning the scientific basis for an influenza vaccine at all. Some point out that the influenza virus isn’t the cause of most flu-like illness, diminishing the advantage that widespread vaccination confers. Others argue that flu shots don’t work well for the most vulnerable among us, including the elderly, because their immune systems are too weak to respond. The most vocal critics even point to studies showing the influenza vaccine is no better than a placebo.

There’s also a safety concern, since many influenza vaccinations contain toxins such as thimerosal, a preservative containing mercury that was removed from most (but not all) children’s vaccines more than a decade ago.

The rising furor over the influenza vaccine differs from the controversy over most other vaccines because the central argument is not over the risk but rather if it works at all. Defenders insist that widespread vaccination will confer a herd immunity to the general population, protecting the weakest among us, who might actually succumb to influenza if exposed. They say that manufacturing an influenza vaccine year after year keeps the factories primed for the dreaded day a more virulent strain threatens a true pandemic, like the one that killed hundreds of thousands of Americans in 1918. But skeptics label such benefits hypothetical at best, and argue that even the smallest risk or side effect is unacceptable.


Origin Story

No one knows for sure when influenza began circulating through human populations, but since highly transmissible viruses require densely inhabited areas to spread, most medical historians trace the disease to the establishment of cities.

The first description of what sounds like influenza comes from the ancient Greek philosopher and physician Hippocrates. Reports of the rapid spread of fever, body aches and respiratory distress were issued regularly in the densely packed Greco-Roman world.
The most severe influenza pandemic to date hit in 1918 and swept the globe for two years, infecting about 30 percent of the human population and killing an estimated 40 to 50 million people (675,000 in the United States alone).

When influenza kills, the most common victims are young children, the elderly and people with compromised immune systems. The great 1918 pandemic was unusual because it claimed the lives of so many healthy young adults. The fierce pathogen was no ordinary influenza strain — it was avian; as a bird flu, it was particularly foreign to the human immune system — which most likely explains the bizarre mortality pattern.

By the 1940s, researchers had classified influenza into multiple types — A, B and C — based on their protein compositions. Eventually, they subdivided these types further, based on external structure, which determines how a particular virus invades and colonizes the human respiratory system.

One category of shell protein, called hemagglutinin (H), is characterized by spiked extensions that spearhead the initial invasion. Another category, called neurminidase (N), helps viral particles capture new terrain once invasion has occurred.

Thus far, three types of H and two types of N have been associated with widespread human infection, giving influenza its dreaded alphanumeric acronyms. H1N1, for instance, is a type-A swine flu that made a landing in 2009.

The increasingly ubiquitous H3N2, another type-A virus that infects humans, pigs and birds, was isolated in the United States as recently as last year.

Chasing Data

When the influenza pandemics of 1957 and 1968 hit, scientists were able to identify the diseases’ predominant viral strains and design preventive vaccines tailored to those strains.

The problem, even back then, was that there were several variations of influenza strains circulating the globe, says medical historian George Dehner, PhD, author of Influenza: A Century of Science and Public Health Response (University of Pittsburgh Press, 2012). The variants of those strains mutated constantly, far too quickly for the vaccines to keep pace.

Over the years, with the advent of new DNA sequencing technologies, scientists have become better at rapidly isolating influenza strains and producing updated vaccines. But it is still an inherently inexact science, unable to keep up with the speed at which viruses can spread and morph, a phenomenon dramatically amplified by global travel in recent years.

Meanwhile, the controversy over vaccination has intensified. Some experts question whether flu inoculations are even focused on the right target. Epidemiologist Tom Jefferson, MD, author for the independent Cochrane Acute Respiratory Infections Group, suggests the incidence of influenza is greatly inflated because it is systematically confused with influenza-like illness, a syndrome caused in minor part by influenza viruses, but more frequently attributable to other viral and bacterial agents. “Conflation of influenza with influenza-like illness has confused the situation and fueled a frenzy,” he says.

Experts like Jefferson caution against using the words “flu” and “influenza” interchangeably, noting that “flu” is a more loosely defined category that includes viruses that are not influenza-based, but just happen to cause very similar clinical symptoms.

To illustrate, Jefferson points to Flu Trends (, a site that estimates flu incidence around the world based on the number of flu-related search queries in each region. “Users of Flu Trends think they are following the spread of influenza,” he notes, “while in reality, the site depicts the spread of influenza-like illness.”

Virologist Kennedy Shortridge, PhD, agrees. “There are a number of infectious agents that can mimic flu,” says Shortridge, a professor emeritus at the University of Hong Kong and a pioneer in studying the origin of influenza. “In many cases, no laboratory diagnosis of influenza is made.”

To find out how many cases of influenza-like illness are actually influenza A or B, scientists would need to take a random sample of people diagnosed with influenza-like illness, and then test them for every possible causal agent and illness. The formal studies are few, but Jefferson has completed calculations based on data from trials for vaccines, and he estimates that, on average, only about 7 percent of those with influenza-like illness actually have influenza.

“The CDC and the media portray influenza as a deadly threat,” he says. “But the data suggest that seasonal influenza is a relatively rare and benign condition, with an incidence not exceeding 1 percent in the general population during autumn and winter months.”

Part of the problem is a lack of evidence for the deaths often attributed to influenza, says Peter Doshi, PhD, a postdoctoral fellow in comparative effectiveness research at Johns Hopkins University School of Medicine in Baltimore. The CDC put the death toll at 36,000 in 2003, though it has recently backed off the claim. “There is no actual body count here, as we have with death by car accident or cancer,” Doshi says. Rather, the numbers are broad estimates, made when the CDC uses statistical modeling to associate “excess deaths” with periods of elevated influenza-virus circulation. “But since there is no guarantee that what they call influenza is actually influenza,” says Doshi, the whole model is unreliable.

Jefferson and his Cochrane team performed a meta-analysis — a study of studies — using the best research data they could find on influenza vaccines. In their subsequent report, published in the British Medical Journal in 2009, they concluded that there was little evidence to support continued widespread use of vaccine for influenza.

On average, says Jefferson, perhaps one adult out of 100 vaccinated will get influenza symptoms compared with two out of 100 in the unvaccinated group.

“After reviewing more than 40 clinical trials, it is clear that the performance of the vaccines in healthy adults is nothing to get excited about,” he says. “Public health interventions such as hygiene measures and barriers to interrupt or reduce the spread of respiratory viruses have a much better evidence base than vaccines. They are also cheaper, yet they are almost ignored.”

An Informed Choice

There are certainly plenty of experts who still endorse the influenza vaccine. One is immunologist Mary Ruebush, PhD, best known for her book, Why Dirt Is Good: 5 Ways to Make Germs Your Friends (Kaplan Publishing, 2009). “Getting the flu vaccine is like taking your immune system to the gym,” Ruebush says. “Your immune system is activated when it responds to the vaccine, keeping it primed for response when the actual virus hits.”

Ruebush and others believe the best course is for the healthy among us to get vaccinated, not so much to protect ourselves from a bout of influenza, but for the benefit of seniors and others who don’t mount enough of an immune response, regardless of whether or not they are vaccinated. The tactic invests a population with what public health experts refer to as “herd immunity.’”

Still, even in healthy populations, vaccines typically protect against just three or four strains, not the multiple strains that are constantly mutating in the wild. So, even if a vaccine boosts immunity, it can never protect against the full range of a constantly shifting illness.

After weighing the benefits of this marginal level of coverage, you might well decide to skip this year’s trip to the clinic. Then again, you may decide something is better than nothing, and elect to follow the advice of mainstream medicine and the CDC.

If you choose the latter path, there are a few things to keep in mind.

First, the flu vaccine is prepared in hen eggs — so if you are allergic to eggs, you could have a reaction. You should also ask questions about the chemical makeup of your shot. The majority of flu vaccines come in multidose vials preserved with thimerosal, a form of the heavy metal mercury that has been widely implicated in neurological and inflammatory disease. (Single-dose vials and the live flu-vaccine mist are generally thimerosal-free.)

Doshi also wants people to know that flu vaccines are biologics, “meaning they are made with living materials,” he says. “Problems with the manufacturing process continue to crop up,” he notes, because dealing with living material presents challenging complexities, and contamination is a near-constant threat.

He points to the recent spike in cases of narcolepsy in Finland and febrile convulsions in Australia in 2009 following vaccination. Use of the respective vaccines was discontinued and the problems disappeared, though the root causes were never determined. “The process is messy,” and it’s impossible for something retooled each year to be risk-free.

Jefferson also points out that advisers on government vaccine committees vested with product approval have suspect ties to the manufacturers. With many of pharma’s most profitable drugs coming off patent in recent years, new vaccines, including influenza vaccines, have taken on an added luster. Experts predict that the seasonal influenza-vaccine market will grow to a $4 billion a year industry by 2015.

Despite all this, Doshi believes that a concern for the public’s well-being is what motivates most health officials. Looming in the back of everyone’s mind, after all, is the fear of another great pandemic. Pharmaceutical companies have convincingly argued that we must maintain a “growing and stable” market for garden-variety annual influenza vaccines. Otherwise, they warn, when the next flu pandemic hits, we won’t have mechanisms in place to stay ahead of the disaster — and we’ll be defenseless in its wake.

Jefferson doesn’t buy this argument: “Vaccine policies are made on the basis of personal belief. Once the policies are made, those who made them publish the evidence to support their point of view. They keep justifying their policy on the basis of studies done by pharmaceutical companies, and they are unwilling to reexamine their decisions and reevaluate the policies.”

Shortridge points out another problem. “When a pandemic virus emerges,” he says, “it takes time for the world to recognize that it is on the cusp of a pandemic. Time for preparation of a vaccine and safety testing hinder widespread distribution and protection.”

Meanwhile, the World Health Organization and the CDC continue to push for widespread influenza vaccination as the most effective means of prevention, and many experts flat-out reject the notion that influenza is benign.

This debate will likely rage for years. So for now, each of us is left to make up our own mind about whether to get that shot — or not.

Pamela Weintraub is executive editor of Discover magazine and the author of Cure Unknown: Inside the Lyme Epidemic (St. Martin’s Press, 2008).

Illustration by from Stuart Bradford

10 flu shot myths

Nobody wants to get the flu. The fever and pains are no fun — and in some cases, the flu can be life-threatening. According to the Centers for Disease and Prevention (CDC), millions of people get the flu every year. Children, pregnant women, and people over 50 especially are at risk.

But many cases of the flu can be prevented by a simple annual shot. So why doesn’t everybody get one? There are some common myths about flu shots that may prevent some people from getting them. Let’s look at each of these myths, and clear them up one by one.

Myth #1: Flu shots can cause the flu

For the 2016 to 2017 flu season, the CDC recommended the use of a vaccine made from an inactivated flu virus. (An inactivated virus is one that is grown in a lab and then killed; the dead virus cannot make you sick, but helps your body build immunity to the live virus.) This year’s version is similar, and — like last year’s — is not capable of causing the flu. In earlier years, some vaccines contained a live, but weakened, flu virus. Even so, they were developed to not make you sick.

Myth #2: You don’t need a flu shot this year if you got one last year

Flu viruses are constantly changing. So vaccines are reviewed every year and updated as needed. Last season’s vaccine was developed to fight last year’s virus, but probably wouldn’t be effective this season. That’s why it’s important to get this year’s flu shot to fight this year’s virus.

Myth #3: Flu shots don’t work

The CDC conducts studies every year to determine how well that season’s vaccine protects people against flu illness. Recent studies show that vaccination reduces the risk of flu illness between 40% and 60% when the vaccines are well-matched against the viruses.

Some people believe that the flu vaccine does not work for children. It’s true that effectiveness varies by age. This is because of the way a child’s immune system changes as they grow. The CDC points to a study that found that “flu vaccines reduced children’s risk of flu-related pediatric intensive care admission by 74%.”

Kaiser Permanente Washington pediatrician and chair of immunizations John Dunn, MD, tells parents, “We get a lot of questions each year about the flu vaccine. The bottom line we tell everyone six months and older is, ‘Get a flu shot.’ You’re much better having the vaccine on board than not. Flu is a serious, potentially fatal illness. A flu vaccine is the best way to make sure you and your loved ones are protected.”

Myth #4: Flu vaccines contain harmful ingredients

Vaccine skeptics point to inactive ingredients used in some versions of flu vaccines. Thimerosal is used as a preservative and formaldehyde is used in killing the live virus to make it inactivated, as noted above. Repeated studies have shown that these substances are not harmful in the tiny amounts contained in flu vaccines.

Myth #5: Pregnant women shouldn’t be vaccinated

Some have claimed that the flu vaccine is linked to miscarriage. This isn’t the case. What is true, however, is that the flu itself is linked to miscarriage. So it’s especially important that pregnant women be vaccinated against the flu. There will be rare cases when a physician advises against this because of an underlying health condition.

Myth #6: Flu shot side effects are worse than the flu itself

The flu vaccine can occasionally cause side effects such as mild aches, fatigue, headache, or fever. Like other injections, a flu shot can cause fainting. The most common side effect is discomfort or minor pain around the site of the injection. Because the flu vaccine does not cause the flu, these symptoms aren’t as severe as those from the flu itself. And the flu can cause serious illness lasting days or weeks.

Myth #7: If I get the flu, antibiotics will make me better

Antibiotics are given to fight bacteria. They have no effect on viruses such as the flu. Taking antibiotics for the flu puts you at unnecessary risk of side effects. Also, this may contribute to you being resistant to antibiotics in the future.

Myth #8: Healthy people don’t die from the flu

Your risk of severe complications from the flu is higher if you have an underlying health condition. But even strong, healthy people can become very ill. Many healthy adults and children are among the thousands of Americans who die each year due to flu-related complications.

Myth #9: There’s no point in getting a flu shot after Thanksgiving

Flu vaccines are helpful as long as viruses are out there. And flu seasons sometimes last into April. The CDC advises people to become vaccinated by the end of October (it takes about two weeks for the vaccine to fully take effect). The longer you wait, the more susceptible you become. But even a late vaccination can help more than no vaccination at all.

Myth #10: I never get the flu so I don’t need to be vaccinated

Just because you’ve been fortunate in the past doesn’t mean you’ll be so this year. As health author Tara Haelle puts it, “Millions of people have never gotten into car accidents. They still wear seat belts and carry insurance.”

Want more local health news, wellness tips, recipes, and more? Subscribe to the Kaiser Permanente Washington newsletter.

Key Facts About Seasonal Flu Vaccine

Flu Vaccination

Why should people get vaccinated against flu?

Influenza is a potentially serious disease that can lead to hospitalization and sometimes even death. Every flu season is different, and influenza infection can affect people differently, but millions of people get flu every year, hundreds of thousands of people are hospitalized and thousands to tens of thousands of people die from flu-related causes every year. An annual seasonal flu vaccine is the best way to help protect against flu. Vaccination has been shown to have many benefits including reducing the risk of flu illnesses, hospitalizations and even the risk of flu-related death in children.

How do flu vaccines work?

Flu vaccines cause antibodies to develop in the body about two weeks after vaccination. These antibodies provide protection against infection with the viruses that are used to make the vaccine.

The seasonal flu vaccine protects against the influenza viruses that research indicates will be most common during the upcoming season. Most flu vaccines in the United States protect against four different flu viruses (“quadrivalent”); an influenza A (H1N1) virus, an influenza A (H3N2) virus, and two influenza B viruses. There are also some flu vaccines that protect against three different flu viruses (“trivalent”); an influenza A (H1N1) virus, an influenza A (H3N2) virus, and one influenza B virus. Two of the trivalent vaccines are designed specifically for people 65 and older to create a stronger immune response.

What kinds of flu vaccines are available?

Yes. There are different influenza vaccine manufacturers and multiple influenza vaccine products licensed and recommended for use in the United States.

CDC recommends use of any licensed, age-appropriate influenza vaccine during the 2019-2020 influenza season, including inactivated influenza vaccine , recombinant influenza vaccine , or live attenuated influenza vaccine (LAIV). No preference is expressed for any influenza vaccine over another. Both trivalent (three-component) and quadrivalent (four-component) influenza vaccines will be available.

Trivalent influenza vaccines include:

  • A trivalent influenza shot made with adjuvant (Fluad), licensed for people 65 years and older.
  • A high-dose influenza vaccine (Fluzone High-Dose), licensed for people 65 years and older.

Quadrivalent flu vaccines include:

  • Standard-dose quadrivalent influenza shots that are manufactured using virus grown in eggs. These include Afluria Quadrivalent, Fluarix Quadrivalent, FluLaval Quadrivalent, and Fluzone Quadrivalent. Different influenza shots are licensed for different age groups. Some are licensed for children as young as 6 months of age. Most influenza shots are given in an arm muscle with a needle. One quadrivalent influenza shot (Afluria Quadrivalent) can be given either with a needle (for people aged 6 months and older) or with a jet injector (for people aged 18 through 64 years only).
  • A quadrivalent cell-based influenza shot (Flucelvax Quadrivalent) containing virus grown in cell culture, which is licensed for people 4 years and older. This season, all four of the vaccine viruses used in Flucelvax have been grown in cells, making the vaccine totally egg-free.
  • Recombinant quadrivalent influenza shot (Flublok Quadrivalent), an egg-free vaccine, approved for people 18 years and older.

There are many vaccine options to choose from, but the most important thing is for all people 6 months and older to get an influenza vaccine every year. If you have questions about which vaccine is best for you, talk to your doctor or other health care professional. More information on approved influenza vaccines for the 2019-2020 influenza season, and age indications for each vaccine are available in CDC’s Table: U.S. Influenza Vaccine Products for the 2019-20 Season

Are any of the available flu vaccines recommended over others?

No. For the 2019-2020 influenza season, CDC and its Advisory Committee on Immunization Practices (ACIP) recommends annual influenza vaccination for everyone 6 months and older with any licensed age-appropriate influenza vaccine including inactivated influenza vaccine (IIV), recombinant influenza vaccine (RIV4) or live attenuated influenza vaccine (LAIV4) with no preference expressed for any one vaccine over another.

Who should get vaccinated this season?

Everyone 6 months of age and older should get an influenza (flu) vaccine every season with rare exception. CDC’s Advisory Committee on Immunization Practices has made this recommendation since the 2010-11 influenza season.

Vaccination to prevent flu is particularly important for people who are at high risk of developing serious flu complications. See People at High Risk of Developing Flu-Related Complications for a full list of age and health factors that confer increased risk.

More information is available at Who Should Get Vaccinated Against Influenza.

Who Should Not Be Vaccinated?

Different influenza vaccines are approved for use in different age groups. In addition, some vaccines are not recommended for certain groups of people. Factors that can determine a person’s suitability for vaccination, or vaccination with a particular vaccine, include a person’s age, health (current and past) and any allergies to influenza vaccine or its components.

  • People who cannot get a influenza shot
  • People who should talk to their doctor before getting the influenza shot

When should I get vaccinated?

You should get a flu vaccine before flu viruses begins spreading in your community, since it takes about two weeks after vaccination for antibodies to develop in the body and provide protection against flu. Make plans to get vaccinated early in fall, before flu season begins. CDC recommends that people get a flu vaccine by the end of October. Getting vaccinated later, however, can still be beneficial and vaccination should continue to be offered throughout the flu season, even into January or later.

Getting vaccinated early (for example, in July or August) is likely to be associated with reduced protection against flu infection later in the flu season, particularly among older adults.

Children who need two doses of vaccine to be protected should start the vaccination process sooner, because the two doses must be given at least four weeks apart.

Where can I get a flu vaccine?

Flu vaccines are offered in many doctor’s offices, clinics, health departments, pharmacies and college health centers, as well as by many employers, and even in some schools.

Even if you don’t have a regular doctor or nurse, you can get a flu vaccine somewhere else, like a health department, pharmacy, urgent care clinic, and often your school, college health center, or workplace.

Visit the HealthMap Vaccine Finderexternal icon to locate where you can get a flu vaccine.

Why do I need a flu vaccine every year?

A flu vaccine is needed every season for two reasons. First, a person’s immune protection from vaccination declines over time, so an annual vaccine is needed for optimal protection. Second, because flu viruses are constantly changing, flu vaccines may be updated from one season to the next to protect against the viruses that research suggests may be most common during the upcoming flu season. For the best protection, everyone 6 months and older should get vaccinated annually.

Does flu vaccine work right away?

No. It takes about two weeks after vaccination for antibodies to develop in the body and provide protection against influenza virus infection. That’s why it’s best to get vaccinated before influenza viruses start to spread in your community.

Vaccine Effectiveness

Influenza vaccine effectiveness (VE) can vary from season to season. The protection provided by an influenza vaccine depends on the age and health status of the person getting the vaccine, and the similarity or “match” between the viruses used to produce vaccine and those in circulation.

While influenza vaccine varies in how well it works, every season influenza vaccines prevent millions of influenza illnesses, tens of thousands of hospitalizations and thousands of deaths.

For more information, see Vaccine Effectiveness – How well do Flu Vaccines Work.

Can I get seasonal flu even though I got a flu vaccine this year?

Yes. It’s possible to get sick with flu even if you have been vaccinated (although you won’t know for sure unless you get a flu test). This is possible for the following reasons:

  • You may be exposed to a flu virus shortly before getting vaccinated or during the period that it takes the body to gain protection after getting vaccinated. This exposure may result in you becoming ill with flu before the vaccine begins to protect you. (Antibodies that provide protection develop in the body about 2 weeks after vaccination.)
  • You may be exposed to a flu virus that is not included in the seasonal flu vaccine. There are many different flu viruses that circulate every year. A flu vaccine is made to protect against the three or four flu viruses that research suggests will be most common.
  • Unfortunately, some people can become infected with a flu virus a flu vaccine is designed to protect against, despite getting vaccinated. Protection provided by flu vaccination can vary widely, based in part on health and age factors of the person getting vaccinated. In general, a flu vaccine works best among healthy younger adults and older children. Some older people and people with certain chronic illnesses may develop less immunity after vaccination. Flu vaccination is not a perfect tool, but it is the best way to protect against flu infection.

What protection does a flu vaccine provide if I do get sick with flu?

Some people who get vaccinated may still get sick. However, flu vaccination has been shown in some studies to reduce severity of illness in people who get vaccinated but still get sick. A 2017 study showed that flu vaccination reduced deaths, intensive care unit (ICU) admissions, ICU length of stay, and overall duration of hospitalization among hospitalized adults with flu. Another study in 2018 showed that a vaccinated adult who was hospitalized with flu was 59 percent less likely to be admitted to the ICU than someone who had not been vaccinated. Among adults in the ICU with flu, vaccinated patients on average spent 4 fewer days in the hospital than those who were not vaccinated.

Vaccine Benefits

What are the benefits of flu vaccination?

There are many reasons to get an influenza (flu) vaccine each year. Below is a summary of the benefits of flu vaccination, and selected scientific studies that support these benefits.

  • Flu vaccination can keep you from getting sick with flu.
    • Flu vaccine prevents millions of illnesses and flu-related doctor’s visits each year. For example, during 2017-2018, flu vaccination prevented an estimated 6.2 million influenza illnesses, 3.2 million influenza-associated medical visits, 91,000 influenza-associated hospitalizations, and 5,700 influenza-associated deaths.
    • During seasons when the flu vaccine viruses are similar to circulating flu viruses, flu vaccine has been shown to reduce the risk of having to go to the doctor with flu by 40 percent to 60 percent.
  • Flu vaccination can reduce the risk of flu-associated hospitalization for children, working age adults, and older adults.
    • Flu vaccine prevents tens of thousands of hospitalizations each year. For example, during 2017-2018, flu vaccination prevented an estimated 91,000 flu-related hospitalizations.
    • A 2014 studyexternal icon showed that flu vaccine reduced children’s risk of flu-related pediatric intensive care unit (PICU) admission by 74% during flu seasons from 2010-2012.
    • In recent years, flu vaccines have reduced the risk of flu-associated hospitalizations among older adultsexternal icon on average by about 40%.
    • A 2018 study showed that from 2012 to 2015, flu vaccination among adults reduced the risk of being admitted to an intensive care unit (ICU) with flu by 82 percent.
  • Flu vaccination is an important preventive tool for people with chronic health conditions.
    • Flu vaccination has been associated with lower rates of some cardiac eventsexternal icon among people with heart disease, especially among those who had had a cardiac event in the past year.
    • Flu vaccination can reduce worsening and hospitalization for flu-related chronic lung disease, such as in persons with chronic obstructive pulmonary disease (COPD).
    • Flu vaccination also has been shown in separate studies to be associated with reduced hospitalizations among people with diabetesexternal icon and chronic lung diseaseexternal icon.
  • Flu vaccination helps protect women during and after pregnancy.
    • Vaccination reduces the risk of flu-associated acute respiratory infection in pregnant women by about one-half.
    • A 2018 studyexternal icon that included influenza seasons from 2010-2016 showed that getting a flu shot reduced a pregnant woman’s risk of being hospitalized with flu by an average of 40 percent.
    • A number of studies have shown that in addition to helping to protect pregnant women, a flu vaccine given during pregnancy helps protect the baby from flu for several months after birth, when he or she is not old enough to be vaccinated.
  • Flu vaccine can be life-saving in children.
    • A 2017 study was the first of its kind to show that flu vaccination can significantly reduce a child’s risk of dying from flu.
  • Flu vaccination has been shown in several studies to reduce severity of illness in people who get vaccinated but still get sick.
    • A 2017 study showed that flu vaccination reduced deaths, intensive care unit (ICU) admissions, ICU length of stay, and overall duration of hospitalization among hospitalized flu patients.
    • A 2018 studyexternal icon showed that among adults hospitalized with flu, vaccinated patients were 59 percent less likely to be admitted to the ICU than those who had not been vaccinated. Among adults in the ICU with flu, vaccinated patients on average spent 4 fewer days in the hospital than those who were not vaccinated.
  • Getting vaccinated yourself may also protect people around you, including those who are more vulnerable to serious flu illness, like babies and young children, older people, and people with certain chronic health conditions.

*References for the studies listed above can be found at Publications on Influenza Vaccine Benefits. Also, see the A Strong Defense Against Flu: Get Vaccinated! pdf icon fact sheet.

Vaccine Match

What is meant by a “good match” between viruses in the vaccine and circulating influenza viruses?

A “good match” is said to occur when the flu vaccine viruses used to produce flu vaccine and the viruses circulating among people during a given influenza season are “like” one another such that the antibodies produced by vaccination protect against infection with circulating viruses.

What if circulating viruses and the vaccine viruses are different?

During seasons when one or more of the circulating viruses are different or “drifted” from the vaccine viruses, vaccine effectiveness against the drifted viruses can be reduced. It’s important to remember that flu vaccine protects against three or four different flu viruses and multiple viruses usually circulate during any one season. Even if the effectiveness of the vaccine is reduced against one virus it can still be effective at preventing flu illness caused by the other circulating viruses. For these reasons, CDC continues to recommend flu vaccination for everyone 6 months and older even if vaccine effectiveness against one or more viruses is reduced.

Why is there sometimes not a good match between a vaccine virus and circulating viruses?

Flu viruses are constantly changing (called “antigenic drift”) – they can change from one season to the next or they can even change within the course of one flu season. Experts must pick which viruses to include in the vaccine many months in advance in order for vaccine to be produced and delivered on time. (For more information about the vaccine virus selection process visit Selecting the Viruses in the Influenza (Flu) Vaccine.) Because of these factors, there is always the possibility of a less than optimal match between circulating viruses and the viruses used to produce vaccine.

The production process for some seasonal vaccines also may impact how well vaccine works against certain viruses, especially influenza A (H3N2) viruses. Growth in eggs is part of the production process for most seasonal flu vaccines. While all influenza viruses undergo changes when they are grown in eggs, changes in influenza A(H3N2) viruses are more likely to result in antigenic changes compared with changes in other influenza viruses. These so-called “egg-adapted changes” are present in most of the vaccine viruses recommended for use in egg-based vaccine production and may reduce their potential effectiveness against circulating influenza viruses. Advances in vaccine production technologies (for example, cell-based and recombinant technology) and advanced molecular techniques are being explored as ways to improve flu vaccine effectiveness. Learn more by visiting, Advancements in Influenza Vaccines.

Will this season’s vaccine be a good match for circulating viruses?

It’s not possible to predict with certainty if a flu vaccine will be like circulating flu viruses because flu viruses are constantly changing. A flu vaccine is made to protect against the flu viruses that research and surveillance indicate will likely be most common during the season. Over the course of flu season, CDC studies samples of circulating flu viruses to evaluate how close a match there is between viruses used to make the flu vaccine and circulating flu viruses. More information about the 2019-2020 flu season and recommended vaccines is available.

Vaccine Side Effects (What to Expect)

Can a flu vaccine give me flu?

No, a flu vaccine cannot cause flu illness. Flu vaccines that are administered with a needle (flu shots) are currently made in two ways: the vaccine is made either with a) flu vaccine viruses that have been killed (inactivated) and are therefore not infectious, or b) with proteins from a flu vaccine virus instead of flu vaccine viruses (which is the case for recombinant influenza vaccine). Nasal spray vaccine is made with attenuated (weakened) live flu viruses, and also cannot cause flu illness. The weakened viruses are cold-adapted, which means they are designed to only cause infection at the cooler temperatures found within the nose. The viruses cannot infect the lungs or other areas where warmer temperatures exist.

What side effects can occur after getting a flu vaccine?

While a flu vaccine cannot give you flu illness, there are different side effects that may be associated with getting a flu shot or a nasal spray flu vaccine. These side effects are mild and short-lasting, especially when compared to symptoms of bad case of flu.

A flu shot: The viruses in a flu shot are killed (inactivated), so you cannot get flu from a flu shot. Some minor side effects that may occur are:

  • Soreness, redness, and/or swelling where the shot was given
  • Headache (low grade)
  • Fever
  • Muscle aches
  • Nausea
  • Fatigue

The nasal spray: The viruses in the nasal spray vaccine are weakened and do not cause severe symptoms often associated with influenza illness. In children, side effects from the nasal spray may include:

  • Runny nose
  • Wheezing
  • Headache
  • Vomiting
  • Muscle aches
  • Fever (low grade)

In adults, side effects from the nasal spray vaccine may include:

  • Runny nose
  • Headache
  • Sore throat
  • Cough

If these problems occur, they begin soon after vaccination and usually are mild and short-lived. A flu shot, like other injections, can occasionally cause fainting. Tell your provider if you feel dizzy or have vision changes or ringing in the ears. As with any medicine, there is a very remote chance of a vaccine causing a severe allergic reaction, other serious injury, or death. People who think that they have been injured by a flu vaccine can file a claim for compensation from the National Vaccine Injury Compensation Program (VICP)external icon.

More information about the safety of flu vaccines is available at Influenza Vaccine Safety.

Vaccine Supply and Distribution

How much influenza vaccine is projected to be available for the 2019-2020 influenza season?

Flu vaccine is produced by private manufacturers, so supply depends on manufacturers. Vaccine manufacturers have projected that they will supply as many as 162 million to 169 million doses of influenza vaccine for the 2019-2020 season.

Where can I find information about vaccine supply?

Information about vaccine supply is available on the CDC’s Vaccine Supply & Distribution webpage.

Special Consideration Regarding Egg Allergy

People with egg allergies can receive any licensed, recommended age-appropriate influenza (flu) vaccine (IIV, RIV4, or LAIV4) that is otherwise appropriate. People who have a history of severe egg allergy (those who have had any symptom other than hives after exposure to egg) should be vaccinated in a medical setting, supervised by a health care provider who is able to recognize and manage severe allergic reactions.

Not long after Labor Day, you’ll start hearing it. “Get your flu shot!” But do you really need to?

Yes. The CDC says everyone over 6 months old should get a flu vaccination every year. It’s the surest way to protect yourself from the flu.

“The flu vaccine stimulates your body to make antibodies,” says Patricia Winokur, MD, a professor of internal medicine and infectious diseases at the University of Iowa. They help your immune system fight flu viruses when you come in contact with them.

You’ve probably heard about someone who got their vaccine but got the flu anyway. It happens, but the vaccine still helps even if you get sick. It makes the illness less severe than it would be without it. People who get a flu shot are less likely to need to go to the hospital.

And even if you’re healthy and not worried about getting sick, get a flu shot to protect your loved ones. Babies, young kids, older adults, and those with chronic health problems can get seriously sick from the flu.

“It provides community protection,” says William Schaffner, MD, medical director of the National Foundation for Infectious Diseases. “You’re much less likely to spread the flu to others . You don’t want to give it to someone at work, in your family, at the gym, at religious services. We get the flu vaccine for ourselves and also for everyone around us.”

Is the Flu Vaccine a Good Idea for Your Family?

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The flu vaccine is a good idea for all families. It does not cause the flu and it helps keep kids and parents from getting sick. Getting the flu is worse than having a cold and can make a person sick for a week or more.

Babies younger than 6 months old can’t get the vaccine. But if their parents, other caregivers, and older kids in the household get it, that will help protect the baby. This is important because infants are more at risk for health problems from the flu.

Who Should Get the Flu Vaccine?

The Centers for Disease Control and Prevention (CDC) recommends a flu vaccine for everyone 6 months of age and older.

But it’s especially important for those who are at greater risk of developing health problems from the flu, including:

  • all kids 6 months through 4 years old (babies younger than 6 months are also considered high risk, but they cannot receive the flu vaccine)
  • anyone 65 years and older
  • all women who are pregnant, are thinking about becoming pregnant, have recently given birth, or are breastfeeding during flu season
  • anyone whose immune system is weak from medicines or illnesses (like HIV infection)
  • people who live in long-term care facilities, such as nursing homes
  • anyone (adults, teens, and kids) with an ongoing medical condition, such as asthma or diabetes
  • kids or teens who take aspirin regularly and are at risk for developing Reye syndrome if they get the flu
  • caregivers or household contacts of anyone in a high-risk group (like children younger than 5 years old, especially those younger than 6 months, and those with high-risk conditions)

Some things might prevent a person from getting the flu vaccine. Talk to your doctor to see if the vaccine is still recommended if your child:

  • has ever had a severe allergic reaction to a flu vaccination
  • has had Guillain-Barré syndrome

What Are the Types of Flu Vaccine?

Two types of flu vaccine are available for the 2019–2020 flu season. Both protect against four types of influenza virus:

  • the flu shot, which is injected with a needle
  • the nasal spray, a mist which gets sprayed into the nostrils

In the past, the nasal spray vaccine wasn’t recommended for kids because it didn’t seem to work well enough. The newer version appears to work as well as the shot. So either vaccine can be given this year, depending on the child’s age and general health.

The nasal spray is only for healthy people ages 2–49. People with weak immune systems or some health conditions (such as asthma) and pregnant women should not get the nasal spray vaccine.

Vaccine shortages and delays sometimes happen. So check with your doctor about vaccine availability, which vaccine is right for your kids, and how many doses they need.

Egg Allergy and the Flu Vaccine

In the past, people with an egg allergy had to check with their doctor about whether the flu vaccine was OK for them because it’s grown inside eggs. But health experts now say that the amount of egg protein in the vaccine is so tiny that it’s safe even for kids with a severe egg allergy. This is especially important during a severe flu season.

Still, a child with an egg allergy should get the flu vaccine in a doctor’s office, not at a supermarket, drugstore, or other venue.

If your child is sick and has a fever, or is wheezing, talk to your doctor about whether to reschedule the vaccine.

When Should Kids Get the Flu Vaccine?

Flu season runs from October to May. It’s best to get a flu shot as early in the season as possible, ideally before the end of October. This gives the body time to build its protection from the flu. But getting the vaccine later in the season is still better than not getting it at all.

Reviewed by: Elana Pearl Ben-Joseph, MD Date reviewed: September 2019

Here’s why you need to get a flu shot, even if you don’t want one

Priya Mistry

It’s no fun having a needle stuck into your arm. But remember: You’re not just getting a flu shot for yourself — you’re protecting your family, friends, coworkers and community, too.

This post is part of TED’s “How to Be a Better Human” series, each of which contains a piece of helpful advice from people in the TED community; browse through all the posts here.

It’s flu season again. Have you gotten your flu shot? Are you wondering whether you really need one? After all, you haven’t come down with the flu in years. Or, are you trying to convince someone else to get theirs?

The flu — short for influenza — remains a highly dangerous disease. Yes, huge strides have been made since the outbreak of the Spanish flu in 1918, which killed tens of millions of people worldwide. (Watch TED-Ed’s “Lessons on the 1918 flu” to find out more.) But there are still up to 5 million severe cases of the flu every year, resulting in hundreds of thousands of deaths.

Why hasn’t the flu been eradicated? “First, there are more than 100 subtypes of the influenza virus, and the ones in circulation change from season to season,” explains physician and educator Melvin Sanicas in a TED-Ed lesson. “And second, the flu’s genetic code allows it to mutate more quickly than many other viruses.”

Here are some of the most common myths about the flu shot — along with a dose of the truth.

Myth #1: Getting a flu shot will give you the flu.

Let’s get it straight: The flu shot will not give you the flu. It contains a deactivated form of the virus, which teaches your body to recognize a real flu virus and respond. Your body should develop the necessary antibodies to the flu within about two weeks of receiving a shot. “You might feel tired and achy after getting it, but that’s not an infection,” says Sanicas. “It’s your normal immune response to the vaccine.”

While some of the other vaccines you get do contain a weakened, live version of the virus they’re protecting you against — such as measles or chickenpox — the flu shot does not have a live virus. Which points to another reason why you need to get a flu shot every year. While just one or two doses of a live vaccine is enough to provide immunity to, say, chickenpox for your entire life, an inactive vaccine like the flu needs to be topped up regularly to maintain your immunity.

Myth #2: At any one time, there are so many different strains of the flu around. A flu shot can’t protect you against all of them — so why bother?

Yes, the flu virus is constantly changing, and that’s why a new flu vaccine is designed by the World Health Organization every year to combat the strains of flu that are predicted to be most prevalent that season. Fun fact: Scientists meet in February to figure out the “recipe” for the flu shot for the northern hemisphere; the southern hemisphere’s “recipe” is determined in September.

For people under 65, you’ll likely be vaccinated against four different kinds of flu (note to the needle-shy: it’s all in one shot — not four jabs). “Even when flu strains mutate further, the vaccine is often close enough that a vaccinated person who catches the flu anyway will have a milder and shorter illness than they would otherwise,” says Sanicas.

Myth #3: The flu shot isn’t needed if a person is young and healthy — it’s intended only for the old and/or sick.

Even if you’re in the prime of life and health, it’s possible to get the flu — especially if your immune system becomes weakened by another illness you catch or by your not getting enough sleep.

There’s another vital reason why the flu shot needs to be distributed as widely as possible, especially in cities: herd immunity. “People who are vaccinated are not only protecting themselves, but by blocking the dissemination of the disease within the community, they are indirectly protecting the people in this community who are not vaccinated,” Buenos Aires-based medical investigator Romina Libster explains in a TEDxRiodelaPlata Talk. “They create a kind of protective shield which prevents them from coming in contact with the disease. This indirect protection that the unvaccinated people within a community receive simply by being surrounded by vaccinated people, is called herd immunity.”

She adds, “Many people in the community depend almost exclusively on this herd immunity to be protected against disease. The unvaccinated people you see in infographics are not just hypothetical. Those people are our nieces and nephews, our children, who may be too young to receive their first shots. They are our parents, our siblings, our acquaintances, who may have a disease or take medication that lowers their defenses. There are also people who are allergic to a particular vaccine. They could even be among any of us who got vaccinated but the vaccine didn’t produce the expected effect, because not all vaccines are always 100 percent effective.”

For herd immunity to work, a large percentage of the population needs to be vaccinated — this is called the threshold. Once vaccination levels drop below the threshold, the disease can spread more easily and that’s when outbreaks of diseases that were previously controlled — such as this year’s worldwide resurgence of measles — will emerge.

If you don’t receive a flu shot and you’re in good health, you may be lucky and avoid getting the flu. However, even if you don’t get sick, you may still be infected by it and spread it to others — a friend who has asthma or diabetes (the US CDC has a long list of those at high risk for flu complications), an immunosuppressed colleague, a newborn or someone else in a high-risk group. The potential complications for people in these categories can be severe, even fatal.

Myth #4: People in the high-risk groups mentioned above should not get flu shots.

Wrong. Pregnant women and many people with chronic health conditions can still get a flu shot, and it’s a good idea for them to do so, given the risks they face if they get the flu. The flu shot has been carefully designed so that it’s safe for as wide a range of people as possible.

If you’re not sure about whether you should get the shot or not, speak to a doctor or a trusted health professional. A small number of people may be allergic to the ingredients in the flu vaccine, but your doctor should be able to advise you based on your medical history.

For those who can’t get a flu shot, herd immunity is vital so it’s up to everyone else to get theirs. No matter how healthy you feel, you can still make someone else dangerously sick.

Watch this TED-Ed lesson on why you need to get a flu shot every year:

Watch this TEDxRiodelaPlata Talk on herd immunity:

About the author

Mary Halton is Assistant Ideas Editor at TED, and a science journalist based in the Pacific Northwest.

  • how to be a better human
  • medicine
  • melvin sanicas
  • Romina Libster
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Is the Flu Vaccine Necessary?

As fall approaches with signs in nearly every grocery store and pharmacy parking lot advertising the flu vaccine, you may wonder: Is the flu vaccine necessary?

Overall, the Centers for Disease Control and Prevention (CDC) recommends all Americans older than six months get the flu vaccine each season and that it’s especially important for people at high risk of flu complications and those who live with or care for them. People at high risk include those with certain medical conditions, such as heart disease, lung disease, HIV and kidney or liver disorders. People who are age 65 and older, pregnant women, and health care professionals are also at risk for flu complications.

Despite these recommendations, opinions differ, even among flu vaccine experts. “There is some controversy surrounding whether or not the flu vaccine is a good idea,” said James Wilde, MD, pediatric emergency medicine physician at Georgia Regents Health System in Augusta who has spent much of his career dealing with flu and prevention. “Personally, I am not a big fan of the flu vaccine,” he said. “I don’t think the flu vaccine is a bad thing, but I do believe it’s only necessary for high risk populations. I don’t agree with the national authorities that say everyone should get a flu vaccine.”

Flu Vaccine and Health

Some research is also less than supportive of the flu vaccine. For instance, a 2011 study, published in the journal Lancet Infectious Diseases, looked at data on the flu vaccine between 1967 and 2011 and reported that, overall, the flu vaccine was only about 60 percent effective in people aged 18 to 65.

Despite skepticism, most medical professionals still recommend the flu vaccine for prevention of flu, particularly among those who are vulnerable to complications. Jon McCullers, MD, Dunavant professor and chair in the department of pediatrics at the University of Tennessee Health Sciences Center and pediatrician-in-chief at Le Bonheur Children’s Hospital in Memphis, is one of them. “I think everyone over age 6 months should get the flu vaccine,” he said.

To make the best decision for yourself and your family members, here are some questions to consider:

How much of a threat is the flu? The flu, or influenza, is a contagious respiratory illness. “The flu is a miserable illness — you are sick for about a week, and the average person misses three days of school or work,” Dr. McCullers said. “So the number one reason to get the flu vaccine is to avoid this.”

The flu virus can also cause complications, including bacterial pneumonia, sinus infections, ear infections, dehydration, and worsening of chronic health conditions, such as diabetes and asthma. It can also be deadly. According to the CDC, between 1976 and 2006, deaths from the flu in a single season have ranged from 3,000 to 49,000 people.

“A big reason to get the flu vaccine is to avoid passing the flu onto your friends and family,” McCullers added. “Most deaths from the flu are in the elderly, in whom the flu vaccine doesn’t work as well, and their only protection may be you not catching the flu and transmitting it to them.”

How effective is the flu vaccine? Truth is, this varies from year to year. “In general, the flu vaccine will protect about two-thirds of persons who take it. However, this is modified by a lot of personal factors, such as age, previous flu vaccines, the circulating virus, and your immune system, so it is hard to make a blanket statement,” McCullers explained.

A large part of the reason for this fluctuation is that medical professionals must predict the dominant strains months before flu season actually begins. Flu vaccine mismatch happens frequently because the virus has a tendency to change rapidly from year to year, Dr. Wilde said.

Will the flu vaccine give me long-term immunity? No, which is why recommendations are to get the flu vaccine every season. In fact, one reason some medical professionals are less than supportive of all people getting a flu vaccine is that they feel antibodies in the vaccine may not be as protective as antibodies that result from actually having had the flu in the past. “During the 2009 H1N1 flu season, those older than 65 were less likely to get the flu and die from it than others; with most flu seasons, we see the opposite,” Wilde explained. He said this could be because older people had or were exposed to the flu strain that first struck with such force in 1918, a strain that closely resembled the 2009 H1N1 flu. “The thought is that these people had antibodies that persisted for their whole lives, so when they were exposed again in 2009, their immune systems recognized it and fought it off. If this is the case, it makes more sense for young healthy people to get the active illness instead of the flu vaccine for maximum immunity,” he said. “When those people reach age 65, taking the flu vaccine might give them additional protection.”

Can I get the flu from the flu vaccine? Despite people who swear the vaccine gave them the flu last year, McCullers said this is medically impossible. “The flu vaccine is usually given in the fall, when a lot of flu-like viruses are circulating, so a common problem is catching another virus around the time when you get the flu vaccine — our brains naturally then like to associate these events,” he said.

After weighing all the information, if you’re still wondering is the flu vaccine necessary, speak to your health care professional. He or she will be able to give you the best advice about whether the flu vaccine is a good idea for you.

What you need to know about the flu shot

Dec. 10, 201300:56

The Flu Comprises More Than One Virus — And So Does The Vaccine

We call it the flu like there’s only one, but every year the flu is different, and is not singular — there are different types of flu viruses. The reason we call it the flu instead of being more specific is because each of the viruses function more or less the same, and because they pop up like clockwork every year in a seasonal epidemic.

“Every winter we know that a flu epidemic will spread around the globe, with maybe three or four strains of the virus the most predominant,” says Dr. Chang, adding that a flu virus typically enters the body through the eyes, nose and mouth. From there it targets the lungs, which is where things can get really bad.

“The flu will cause all the usual upper respiratory symptoms, but it can also cause viral pneumonia or viral lower respiratory infection which can be more serious, and if you have a very severe flu infection, other organs in the body can be affected,” says Chang.

With so many viruses circulating, it’s a yearly challenge for scientists to predict which three or four will prove to be the season’s most prevalent and potent flu viruses.

“Predicting what the predominant strains of the flu will be each winter is done through a lot of surveillance around the world,” says Chang. “We look at all the cases of flu that happen around the world to try to predict each season in advance.”

Once they pinpoint the strains that appear to be the epidemic ones, scientists grow the vaccines either in chicken eggs, or in specialized bacteria. Then they inactivate the virus; “essentially they kill it and chop it up,” explains Chang, adding that this is not the only way to engineer a flu vaccine but it is currently the most common. These dead flu parts get packaged with other ingredients needed to make a vaccine (a concoction of proteins, fats, and antigens).

It Is Impossible For The Vaccine To Give You The Flu

The fact that the viruses in the vaccine are dead is a critical point: a dead virus cannot infect you. It just can’t.

“A lot of times people will say they or their children got the flu from the vaccine, and that is just not possible,” notes Chang. “That said, some people do feel bad after: muscle aches, low grade fever, achy arm . I always tell patients that this is good in the sense that it means your immune system is having a response, which is what we want.”

What you don’t want is an allergic reaction, of course — but these are exceedingly rare.

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The fact that the viruses in the vaccine are dead is a critical point: a dead virus cannot infect you. It just can’t.

“If after getting the vaccine there is any difficulty breathing, swelling of face or tongue or blockage of airways, that is a severe allergic reaction,” says Chang. Patients should also keep an eye on their temperature. A fever of around 101 degrees is common. A Tylenol should help reduce this and other symptoms, but if you’re still ill or getting worse after 48 hours, or if the site of injection is swelling tremendously to the point where you cannot move it — get to the doctor.

Chang notes that even if you’re among the lucky few who feel totally fine after the flu shot with no soreness or low fever, this does not mean your immune system didn’t respond or that the flu vaccine didn’t work.

When To Get The Shot And How Long It Lasts

Now, let’s say you get the flu shot and two days later you get the flu. Well, you didn’t get sick because of the vaccine (because again, dead viruses are non-infectious), but it does point to a loophole: the vaccine takes two to three weeks to have full effect. This is why doctors recommend getting it as soon as it’s available.

If you get the vaccine now, you should be covered through the duration of the flu season, which can start as early as mid-fall, and end as late as early spring. How long the vaccine lives in your system depends on your immune system, but for the general patient it’s between six months and a year.

“The vaccine is not that long-lived in part because the viruses that cause the flu are very smart and keep changing to infect us,” says Dr. Megha Tewari, a family medicine doctor at Memorial Hermann Medical Group. “This is why I tell my patients to get the flu shot every year.”

The Goal Of The Vaccine Is Not Necessarily To Prevent Flu

Optimally, the flu vaccine will prevent you from getting the flu, but that’s actually secondary to the primary goals of the vaccine which are to prevent epidemic and to reduce the cases of severe flu infection.

How long the vaccine lives in your system depends on your immune system, but for the general patient it’s between six months and a year.

“At its most effective the flu shot would prevent you from getting the flu, but really when you look at studies, the purpose of the vaccine is to reduce the number of severe flu illnesses that require going to the hospital,” says Chang. “In other words if you get the flu vaccine, the real goal is even if you do get the flu that you are not as sick as you would be if you had not gotten the vaccine.”

Basically, if your immune system is primed to deal with the virus, should it still attack you, you likely won’t develop a severe flu infection.

Another purpose of the flu vaccine: not everyone can get it, so it’s important that people who can receive it do so that “we build herd immunity,” says Dr. Tewari.

“A lot of patients who have immunological diseases, or an organ transplant, have cancer or other conditions may not be strong enough to get a flu vaccine,” Tewari adds. “But if those around them are vaccinated, we develop a herd immunity, so that hopefully the few people who can’t get the vaccine will not get infected.”

The vast majority of people over the age of six months are A-OK to get a flu shot. Both Dr. Chang and Dr. Tewari insist that there are very few exceptions. Even if you have an egg allergy (remember flu vaccines are often cultivated in eggs) your doctor can recommend an alternate type of vaccine if needed.

What If I’m Pregnant?

Just last week there was a study published suggesting that the flu vaccine could be associated with early-term miscarriage in some pregnant women. But this finding is far from conclusive, and doctors still advise pregnant women to get the flu shot.

“Let’s be clear: this study does not suggest the flu vaccine can cause an increased risk of miscarriage,” says Dr. Sherry Ross an OB/GYN at Providence Saint John’s Health Center. “The flu is more likely to cause serious illness in pregnancy compared to those women who are not pregnant in pregnancy there are changes in the immune system, heart and lung function that make pregnant women more prone to severe illness from the flu which can lead to hospitalization or even death. Other problems as a result of the flu include dehydration, miscarriage and preterm labor.”

Furthermore, a flu shot helps protect newborns from getting the flu.

“Babies can’t get the flu vaccine until thy are six months, so by getting the vaccine herself, the mom will make the antibodies and pass it onto the baby, protecting them from severe flu for the first months of their lives,” says Dr. Chang.

Still, it is totally understandable to be concerned, so if you are pregnant and have questions, talk to your OB/GYN. And if you’re a parent who is unsure if your six month old is really ready for the flu vaccine, pay a visit to your pediatrician.

“If anything it’s a good excuse for a well baby visit,” adds Chang, who admits that as a pediatrician he holds some bias when recommending that parents take their little ones to the pediatrician for their flu shots, but says he doesn’t see any problem with having them administered at your local pharmacy.

Children, like elderly people, are indeed more susceptible to developing severe flu. This is in part because they’re ultra exposed in schools and daycare facilities (and you know, they may not have the best hand hygiene), but also because their immune systems haven’t been toughened up.

“Children have had less experience with flu, whereas adults have more antibody from previous infections,” says Dr. James D. Cherry, a distinguished research professor at the David Geffen School of Medicine at UCLA and UCLA Mattel Children’s Hospital.

Flu Shots Are Critical If You’re In A Disaster Affected Area

While doctors recommend that virtually everybody get their flu shot, Dr. Tewari, based in Houston, Texas makes the timely point that if you are in a disaster-affected area, it’s particularly critical.

“Hurricane Harvey and the other natural disasters affecting many have brought dirty water, and viruses are not visible like mold so we don’t even know what’s in the air,” says Tewari. “People have been displaced, are living in shelters, wearing borrowed clothes and eating donated food. You just don’t know what you’re being exposed to. Plus, when you’re stressed your immunity gets lowered.”

How to Make an Emergency Go Bag

Aug. 28, 201901:08

For many of those still in the midst of natural disasters, a flu shot may sound like a ridiculous luxury at the moment, but it should be noted that many schools and county health departments run programs offering free flu shots. Even if you have health insurance, your flu shot may actually not be covered, so check with your provider. Presently the cheapest flu shot available looks to be at Costco, for $20.

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7 Reasons You Need to Get a Flu Shot This Year

Learn the truth about the flu shot and why you should definitely get one this season.

(September 13, 2019)

As the seasons begin to change, respiratory infections are on the rise, and it’s time to get your annual flu shot. Influenza, or the flu, is a serious and highly contagious illness. Each year, between 9.4 million and 49 million people in the U.S. contract the flu. That is why the CDC urges everyone 6 months of age and older to get a flu vaccine every season. In particular, this year the American Lung Association, the American Diabetes Association (ADA), and the American Heart Association (AHA) have come together to urge the 117 million adults living with chronic disease to prioritize annual flu vaccination.

If you are considering skipping your annual vaccination, here are reasons you may want to reconsider.

  1. The flu shot can be lifesaving.

    Depending on the flu virus’ severity, deaths as a result of flu complications can range from 12,000 to 79,000 people nationwide. The 2017-2018 season specifically reported close to 80,000 casualties of the flu, according to the CDC.

    While anyone can get the flu, certain groups are at increased risk of flu-related complications, including young children, pregnant women, and adults 65 years of age and older. That is why it is essential that these groups get an updated flu vaccine every year.

  2. The flu shot can’t give you the flu, but it can reduce the severity.

    It has been scientifically proven that getting the flu shot won’t cause you to get the flu. This is because each vaccine either contains a dead virus or only includes the single gene of the virus, making it inactive. Another common argument for not receiving the flu shot is that each vaccine only addresses a few strains, so you can still contract the flu even after you are vaccinated. Though this may be true, the CDC does extensive research to ensure that the flu shot is highly effective and is protecting you from several of the most common types that year. Furthermore, studies have found that even if you contract the disease, receiving the flu shot can lessen symptoms considerably, making the sickness shorter and more manageable.

  3. The flu shot helps protect the people around you.

    The flu is highly contagious, so the chance of spreading it to family and friends is extremely likely. Getting the flu shot not only protects you from getting sick, but it also makes sure that those around you, especially those at high risk for infection, remain safe.

  4. It may prevent other serious medical complications for people with chronic conditions.

    During the 2018-2019 season, 93 percent of adults hospitalized for flu, reported at least one underlying medical condition that placed them at high-risk for complications. Recent research has found that not only has the flu shot reduced the number of people who end up hospitalized by almost half, but it has specifically reduced the number of cardiac events, diabetic emergencies and chronic lung complications.

  5. You need a new flu shot annually to stay healthy.

    Flu viruses are constantly adapting so each year a new formula is calculated to address the most common predicted types that season. For the best protection, vaccinations should start after 6 months of age, and continue annually.

  6. The earlier you get it, the safer you’ll be.

    Since it takes about two weeks for the antibodies that protect against flu to develop in the body, you should get the flu shot as soon as the season starts. For many, this means before the end of October. But it’s better to get it later than not at all, which is why many locations offer the vaccine into January or even later.

  7. They are easily and readily available.

    Getting a flu shot has become extremely simple and convenient because flu vaccines are offered at many regularly visited locations. Some places you may be able to find the flu vaccine include doctor’s offices, clinics, health departments, pharmacies and college health centers, as well as by many employers, and even in some schools. To find a location near you, visit our Find a Flu Shot page and learn more about preventing the flu.

The American Lung Association, the American Diabetes Association and the American Heart Association offer educational resources about the burden of flu and increased need for vaccination among people with chronic health conditions. And throughout the flu season, the Lung Association, AHA and ADA will be sharing the personal stories of individuals affected by the flu, resources on how to find the closest flu vaccine provider and debunk myths surrounding the flu. Free, downloadable information on flu and chronic health conditions is also available through the National Foundation for Infectious Diseases and the Centers for Disease Control and Prevention.

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