Misconceptions about Seasonal Flu and Flu Vaccines
Misconceptions about Flu Vaccines
Misconceptions about Flu Vaccines
Can a flu vaccine give you the flu?
No, flu vaccines cannot cause flu illness. Flu vaccines given with a needle (i.e., flu shots) are currently made in two ways: the vaccine is made either with a) flu viruses that have been ‘inactivated’ (killed) and that therefore are not infectious, or b) using only a single gene from a flu virus (as opposed to the full virus) in order to produce an immune response without causing infection. This is the case for recombinant influenza vaccines.
Are any of the available flu vaccines recommended over the others?
CDC recommends use of any licensed, age-appropriate influenza vaccine (inactivated influenza vaccines [IIV], recombinant influenza vaccine [RIV], or live attenuated influenza vaccine [LAIV4]) with no preference expressed for one vaccine over another during the 2018-2019 flu season. Nasal spray vaccine (LAIV4) is again a recommended option for people for whom it is otherwise appropriate. Different flu vaccines are approved for use in different 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 flu vaccine or its components.
Unlike the flu shot, the nasal spray flu vaccine (also known as the “live attenuated influenza vaccine” or “LAIV”) does contain live influenza viruses, but the viruses are attenuated (weakened), so that they will not cause flu illness. In addition, these weakened viruses are cold-adapted, which means they are designed to only replicate (multiply) at the cooler temperatures found within the nose. These viruses cannot infect the lungs or other areas where warmer temperatures exist.
Is it better to get the flu than the flu vaccine?
No. Flu can be a serious disease, particularly among young children, older adults, and people with certain chronic health conditions, such as asthma, heart disease or diabetes. Any flu infection can carry a risk of serious complications, hospitalization or death, even among otherwise healthy children and adults. Therefore, getting vaccinated is a safer choice than risking illness to obtain immune protection.
Do I really need a flu vaccine every year?
Yes. CDC recommends a yearly flu vaccine for just about everyone 6 months and older, even when the viruses the vaccine protects against have not changed from the previous season. The reason for this is that a person’s immune protection from vaccination declines over time, so an annual vaccination is needed to get the “optimal” or best protection against the flu.
Why do some people not feel well after getting the seasonal flu vaccine?
Some people report having mild reactions to flu vaccination. The most common side effects from flu shots are soreness, redness, tenderness or swelling where the shot was given. Low-grade fever, headache and muscle aches also may occur. If these reactions occur, they usually begin soon after the shot and last 1-2 days. In randomized, blinded studies, where some people get inactivated flu shots and others get salt-water shots, the only differences in symptoms was increased soreness in the arm and redness at the injection site among people who got the flu shot. There were no differences in terms of body aches, fever, cough, runny nose or sore throat.
Side effects from the nasal spray flu vaccine may include: runny nose, wheezing, headache, vomiting, muscle aches, fever, sore throat and cough. If these problems occur, they usually begin soon after vaccination and are mild and short-lived. The most common reactions people have to flu vaccines are considerably less severe than the symptoms caused by actual flu illness.
What about serious reactions to flu vaccine?
Serious allergic reactions to flu vaccines are very rare. If they do occur, it is usually within a few minutes to a few hours after the vaccination. While these reactions can be life-threatening, effective treatments are available.
What about people who get a seasonal flu vaccine and still get sick with flu symptoms?
There are several reasons why someone might get a flu symptoms, even after they have been vaccinated against flu.
One reason is that some people can become ill from other respiratory viruses besides flu such as rhinoviruses, which are associated with the common cold, cause symptoms similar to flu, and also spread and cause illness during the flu season. The flu vaccine only protects against influenza, not other illnesses.
Another explanation is that it is possible to be exposed to influenza viruses, which cause the flu, shortly before getting vaccinated or during the two-week period after vaccination that it takes the body to develop immune protection. This exposure may result in a person becoming ill with flu before protection from the vaccine takes effect.
A third reason why some people may experience flu like symptoms despite getting vaccinated is that they may have been exposed to a flu virus that is very different from the viruses the vaccine is designed to protect against. The ability of a flu vaccine to protect a person depends largely on the similarity or “match” between the viruses selected to make the vaccine and those spreading and causing illness. There are many different flu viruses that spread and cause illness among people. For more information, see Influenza (Flu) Viruses.
The final explanation for experiencing flu symptoms after vaccination is that the flu vaccine can vary in how well it works and some people who get vaccinated may still get sick.
Can vaccinating someone twice provide added immunity?
In adults, studies have not shown a benefit from getting more than one dose of vaccine during the same influenza season, even among elderly persons with weakened immune systems. Except for some children, only one dose of flu vaccine is recommended each season.
Is it true that getting a flu vaccine can make you more susceptible to other respiratory viruses?
There was one study (published in 2012) that suggested that influenza vaccination might make people more susceptible to other respiratory infections. After that study was published, many experts looked into this issue further and conducted additional studies to see if the findings could be replicated. No other studies have found this effect. For example, this article [99 KB, 5 pages] in Clinical Infectious Diseases (published in 2013). It’s not clear why this finding was detected in the one study, but the preponderance of evidence suggests that this is not a common or regular occurrence and that influenza vaccination does not, in fact, make people more susceptible to other respiratory infections.
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Misconceptions about Flu Vaccine Effectiveness
Influenza vaccine effectiveness (VE) can vary from year to year, by virus type and subtype, and among different age and risk groups. For more information about vaccine effectiveness, visit How Well Does the Seasonal Flu Vaccine Work)?
There are many reasons to get a 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 2016-2017, flu vaccination prevented an estimated 5.3 million influenza illnesses, 2.6 million influenza-associated medical visits, and 85,000 influenza-associated hospitalizations.
In seasons when the vaccine viruses matched circulating strains, 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 2016-2017, flu vaccination prevented an estimated 85,000 flu-related hospitalizations.
A 2014 study 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 adults 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.
Vaccination helps protect women during and after pregnancy.
Vaccination reduces the risk of flu-associated acute respiratory infection in pregnant women by up to one-half.
A 2018 study showed that getting a flu shot reduced a pregnant woman’s risk of being hospitalized with flu by an average of 40 percent.
Getting vaccinated can also protect a baby after birth from flu. (Mom passes antibodies onto the developing baby during her pregnancy.)
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 infection for several months after birth, when he or she is not old enough to be vaccinated.
Flu vaccine can be life-saving in children.
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 study 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 Why Get a Flu Vaccine[237 KB, 2 pages] fact sheet.
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Misconceptions about the Timing of Seasonal Influenza Vaccination
Should I wait to get vaccinated so that my immunity lasts through the end of the season?
CDC recommends that people get a flu vaccine by the end of October. Getting vaccinated later, however, can still be beneficial. As long as flu viruses are circulating, it is not too late to get vaccinated, even in January or later. While seasonal flu outbreaks can happen as early as October, most of the time flu activity peaks between December and February, although activity can last as late as May. Since it takes about two weeks after vaccination for antibodies to develop in the body that protect against flu virus infection, it is best that people get vaccinated in time to be protected before flu viruses begin spreading in their community.
How long you are immune or your “duration of immunity” is discussed in the ACIP recommendations. While delaying getting of vaccine until later in the fall may lead to higher levels of immunity during winter months, this should be balanced against possible risks, such as missed opportunities to receive vaccine and difficulties associated with vaccinating a large number of people within a shorter time period.
Is it too late to get vaccinated after Thanksgiving (or the end of November)?
No. Vaccination can still be beneficial as long as flu viruses are circulating. If you have not been vaccinated by Thanksgiving (or the end of November), it can still be protective to get vaccinated in December or later. Flu is unpredictable and seasons can vary. Seasonal flu disease usually peaks between December and March most years, but disease can occur as late as May.
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Misconceptions about Physician Consent for Vaccination
Do pregnant women or people with pre-existing medical conditions need special permission or written consent from their doctor to receive the flu vaccine?
No. There is no recommendation for pregnant women or people with pre-existing medical conditions to seek special permission or secure written consent from their doctor for vaccination if they get vaccinated at a worksite clinic, pharmacy or other location outside of their physician’s office. With rare exception, CDC recommends an annual flu vaccine for everyone 6 months and older, including pregnant women and people with medical conditions.
A variety of flu vaccine products are available (Table 1). Vaccine providers should be aware of the approved age indications of the vaccine they are using and of any contraindications or precautions. Providers also should appropriately screen all people getting vaccinated for allergies to vaccine components or other contraindications. People who have previously had a severe allergic reaction to influenza vaccine or any of its ingredients should generally not be vaccinated.
There are some people who should not get a flu vaccine without first speaking with their doctor. These include:
People who have a moderate-to-severe illness with or without a fever (they should wait until they recover to get vaccinated), and
People with a history of Guillain-Barré Syndrome (a severe paralytic illness, also called GBS) that occurred after receiving influenza vaccine and who are not at risk for severe illness from influenza should generally not receive vaccine. Tell your doctor if you ever had Guillain-Barré Syndrome. Your doctor will help you decide whether the vaccine is recommended for you.
Pregnant women or people with pre-existing medical conditions who get vaccinated should get the flu shot.
If a person is vaccinated by someone other than their primary health care provider, the vaccinating provider should ensure that the patient and, if possible, the patient’s medical provider have documentation of vaccination.
For a complete list of people who should not get the vaccine before speaking with their doctor, please review the influenza Vaccine Information Statement for the flu shot.
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Misconceptions about “Stomach Flu”
Is the “stomach flu” really the flu?
No. Many people use the term “stomach flu” to describe illnesses with nausea, vomiting or diarrhea. These symptoms can be caused by many different viruses, bacteria or even parasites. While vomiting, diarrhea, and being nauseous or “sick to your stomach” can sometimes be related to the flu — more commonly in children than adults — these problems are rarely the main symptoms of influenza. The flu is a respiratory disease and not a stomach or intestinal disease.
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PERSONAL HEALTH
Myths About the Flu Vaccine
BY JANE E. BRODY
On Dec. 20, 1968, I got the flu. I remember it still: Christmas was a washout — I couldn’t leave the bed unassisted or keep anything down, not even a taste of the goose that someone else had to cook.
On New Year’s Day I could hardly breathe, and my husband carried me to a doctor, who diagnosed double pneumonia. I didn’t recover fully for three months. And I was pregnant — with twins, no less.
The flu is no joke, especially not for pregnant women, the very young and the elderly, people who are chronically ill and those whose immune systems are suppressed. I managed to contract the flu during each of the three major outbreaks of Type A virus between 1957 and 1977. I never again want to be that sick — and I haven’t been. I get a flu shot every fall before the season begins.
But as this year’s severe epidemic demonstrated, too many people are neglecting this most basic precaution.
Although annual flu vaccination is now recommended for nearly everyone over the age of 6 months, for one reason or another only a minority of Americans — and fewer than half of those most at risk of serious complications and death from the flu — take this advice. Only two-thirds of health care workers, in fact, got the flu vaccine last year.
Recently I overheard a father say: “I’m not getting my kids vaccinated. I found out it’s mainly to protect the elderly, and there are no old people in my house.”
I thought: Maybe not, sir, but do your children never go out? What about the people they may infect in school, in other people’s houses, or in a movie theater, store, public restroom, train, plane or bus?
Almost anywhere they go, these children could come in contact with a cancer patient on chemotherapy, a pregnant woman, or someone with asthma, diabetes, heart disease or a kidney or liver disorder. All are especially at risk of serious complications or death from the flu.
According to the Centers for Disease Control and Prevention, the flu virus can travel six feet on droplets from coughs, sneezes or talk. Those infected can spread the virus before symptoms develop and for a week or more after getting sick. Less often, flu is spread by touching a contaminated surface, then touching one’s eyes, nose or mouth.
Even if all those at high risk got their shots, the vaccine does not work for everyone; many can still get the flu, develop pneumonia or a worsening of a chronic condition, and die. But when more people are immunized, fewer get sick and the chances of keeping everyone else healthy improve, a phenomenon called “herd immunity.”
Dr. Thomas R. Talbot and his wife, Dr. H. Keipp Talbot, infectious disease specialists at Vanderbilt University School of Medicine, recently examined — and refuted — many of the common arguments against influenza vaccination.
“The vaccine doesn’t work.” While it is not as effective as many other popular vaccines (on average, the flu vaccine is 56 percent effective in preventing flu), it is not ineffective.
The flu viruses in circulation change from year to year. The decision as to which variants to include in the vaccine each year must be made well in advance of the flu season. At any point thereafter, a new variant may emerge or an old one re-emerge, as happened this year with the Type B flu virus.
The vaccine’s effectiveness varies by population, too. This year’s vaccine has been only 9 percent effective in protecting the elderly, for instance. Still, Dr. Thomas Talbot said, “even though elderly people who are immunized may get sick, they may not get as sick. They may still go to the doctor, but not to the hospital.”
“Certain populations don’t respond as well to the vaccine — the very young and very old, people who are immunosuppressed and women who are pregnant,” he added. “People who respond best to the vaccine should be immunized so they don’t spread it to others.”
Over all, this year’s vaccine proved 62 percent effective in preventing illness that warranted a doctor’s attention. Immunization is one good way to reduce the nation’s skyrocketing health care costs.
“The vaccine causes the flu.” No way! There are two kinds of licensed flu vaccines: an inactivated kind made with dead virus and one prepared with live “attenuated” virus. Neither is capable of reproducing in the human body. Those who say they got sick right after getting the shot most likely were already infected. Or they developed another viral infection unrelated to flu.
“I’m allergic to eggs.” The vaccine is prepared in eggs, but only those with a severe anaphylactic reaction to eggs must avoid it. Based on recent evidence, the vaccine is safe for those with lesser reactions (for example, only hives) as long as they are observed for half an hour after receiving it.
“I am pregnant or chronically ill, or live with someone whose immune system is compromised.” These are the very people for whom the flu vaccine is most important, because they face the greatest risk of complications. “The vaccine is safe in these persons and can prevent serious morbidity and mortality,” the Talbots wrote.
“I never get the flu.” Although some who are infected may not develop classic flu symptoms (fever, cough, muscle or body aches, sore throat, headache, fatigue, runny or stuffy nose), they can still transmit the virus to others at home, school or work.
Even if you were not immunized and already had the flu this season, you’d be wise to get the vaccine; you can still be sickened by another of the viral variants circulating. Flu season, which peaks in February, can last until May. And because immunity to flu viruses tends to be short-lived, having had the flu or the vaccine in past years is not sufficiently protective.
Inconvenience — getting a doctor’s appointment and waiting in the office — might have once been a reasonable excuse to skip a flu shot. Nowadays, access to the vaccine is widespread: in pharmacies, stores, clinics, health departments and schools and at work, as well as at doctors’ offices. Often, as for people on Medicare, there is no charge for the vaccine.
