When Should People Get The Flu Vaccine
Flu season runs from October to May. It’s best to get a flu vaccine as early in the season as possible, ideally by the end of October. This gives the body a chance to make antibodies that protect from the flu. But getting a flu vaccine later in the season is better than not getting it at all. Getting a missed flu vaccine late in the season is especially important for people who travel. That’s because the flu can be active around the globe from April to September.
What Kinds Of Flu Shots Are There
Flu shots known as “quadrivalent vaccines” protect against four strains of flu virus. These include two influenza A strains H1N1 and H3N2 and two influenza B strains. Previously, some flu shots protected against three strains, and were known as trivalent flu vaccines, but starting in the 2021-2022 season, all flu shots are quadrivalent, according to the CDC.
In addition to the standard-dose flu vaccine given through a needle, flu shots are available in several different forms. These include a high-dose version for those ages 65 and older a “cell-based” version that’s grown in animal cells rather than hen’s eggs and is approved for people ages 4 and older a “recombinant” vaccine that does not use the full influenza virus or chicken eggs in the production process and is approved for people ages 18 and older and a nasal spray, which is approved for healthy people ages 2 to 49, but not for pregnant women.
There is also a needle-free flu shot, delivered by a so-called jet injector, which uses a high-pressure stream of fluid to inject the vaccine, the CDC says. It is approved for adults ages 18 to 64.
Which Adults Should Not Get The Flu Vaccine
You should NOT get the influenza vaccine if you:
- Developed Guillain-Barre syndrome within six weeks of receiving the flu vaccine in the past
- Had a severe reaction to the flu vaccine in the past
- Have a severe allergy to any vaccine component
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It’s long been advised that people with allergies to eggs should not get the flu shot. However, the American College of Allergy, Asthma and Immunology says the vaccine contains such a low amount of egg protein that it’s unlikely to cause an allergic reaction in those with an egg allergy. If you have a severe egg allergy , talk to your doctor before getting the flu vaccine. Also, as mentioned above, flu vaccines not made with eggs are available.
The nasal spray flu vaccine can only be used in healthy, younger adults who are not pregnant. In addition to the previously listed adults who should not receive the flu shot, adults should NOT get the nasal spray influenza vaccine if they:
- Are pregnant
- Are ages 50 or older
- Have a weakened immune system
- Have a long-term health condition, such as diabetes, kidney disease, or heart or lung disease, including asthma
- Have a muscle or nerve condition that can cause problems with breathing or swallowing
- Have a nasal condition that could make breathing difficult
due to disease or certain medical treatments
Have a weakened immune system
You should not get the nasal spray flu vaccine if you are in contact with people who have a severely weakened immune system.
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Common Flu Shot Side Effects You Should Know
The US Centers for Disease Control and Prevention recommends annual flu vaccination for everyone age 6 months or older. It is best to get vaccinated by end of October or early November before the flu season begins.
The flu vaccine may prevent you from getting sick with influenza, but the shot itself may cause some side effects, which are very similar to symptoms of the flu. In addition to the pain, redness or swelling near the shot, you may experience headaches, muscle soreness, fever and nausea after getting the flu vaccine.
Previous Findings On Serial Vaccination

A number of previous studies have raised the possibility that consecutive-year flu vaccination may sometimes backfire, resulting in reduced VE the second year. In particular, signs of this were seen in the 2014-15 flu season, when H3N2 was the dominant subtype and flu vaccines performed unusually poorly in both Canada and the United States. The H3N2 component in the vaccine that year was the same as the year before, and it didn’t match well with a new H3N2 “drift” variant circulating in the population.
Researchers use the term “antigenic distance hypothesis” to describe the possible negative effects of serial flu vaccination. The hypothesis, according to the JID report, predicts that a prior season’s influenza vaccine may interfere negatively with the effectiveness of the current season’s vaccine when the difference, or antigenic distance, between the two vaccines is small but the difference between the vaccine strains and the current epidemic strain is large.
The team found that the effects of prior-year vaccination varied significantly by season, which they said was consistent with the antigenic distance hypothesis.
In 2010-11, when the prior-year and current vaccine strains were different, prior-year vaccination did not interfere with protection. Compared with unvaccinated patients, VE for those vaccinated only in 2010-11 was estimated at 34% , and VE for those vaccinated both the prior and current year was also 34% .
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Do Flu Vaccines Cause Any Side Effects
Like any medical product, vaccines can cause side effects. Side effects of the flu vaccine are generally mild and go away on their own within a few days.
Common side effects from the flu shot include:
- Soreness, redness, and/or swelling from the shot
- Headache
- Muscle aches
The flu shot, like other injections, can occasionally cause fainting.
Some studies have found a possible small association of injectable flu vaccine with Guillain-Barré syndrome . Overall, these studies estimated the risk for GBS after vaccination as fewer than 1 or 2 cases of GBS per one million people vaccinated. Other studies have not found any association. GBS also, rarely, occurs after flu illness. Even though GBS following flu illness is rare, GBS is more common following flu illness than following flu vaccination. GBS has not been associated with the nasal spray vaccine.
Vaccines Are Eliminated Quickly
Unlike many medications, which are taken daily, vaccines are generally one-and-done. “Medicines you take every day can cause side effects” that reveal themselves over time, including long-term problems as levels of the drug build up in the body over months and years, Goepfert said. But “vaccines are just designed to deliver a payload and then are quickly eliminated by the body,” he said. “This is particularly true of the mRNA vaccines. mRNA degrades incredibly rapidly. You wouldn’t expect any of these vaccines to have any long-term side effects. And in fact, this has never occurred with any vaccine.”
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Will The Flu Vaccine Help Fight The Coronavirus
The coronavirus and influenza are two different illnesses caused by different viruses. The flu shot will not help fight coronavirus infection, but getting a flu shot remains an important step in protecting your health and in reducing the overall burden of respiratory illness in the community. Having enough people vaccinated against the flu ensures that hospitals and clinics keep adequate space to treat patients with coronavirus infections. It is expected that both the coronavirus and the flu may be present at the same time in the 2020-21 flu season, and being vaccinated against the flu helps protect yourself and vulnerable populations against an illness that might happen at the same time as a coronavirus infection.
The Flu Shot Is Effective
The effectiveness of the vaccine varies from season to season. It depends on:
- how well the vaccine matches with the circulating flu viruses
- the health and age of the person getting the flu shot
The viruses circulating in the population can sometimes change during the time it takes to produce a vaccine. When this happens during the flu season, the flu shot may not work as well as expected.
It’s also important to remember that the flu shot protects against several different flu viruses each season. The seasonal flu shot can still provide protection against the remaining 2 or 3 viruses, even when theres:
- a less-than-ideal match
- lower effectiveness against one virus
If you do get the flu, the flu shot may reduce the severity of flu-related complications.
Getting your flu shot is still the most effective way to protect yourself against the flu and flu-related complications.
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Should People Who Are Immunocompromised Get A Flu Shot
Another misconception is that individuals with chronic conditions who may be immunocompromised may have a worse reaction to the vaccine because they are more vulnerable. Health officials say this is not so.
When we say that the vaccine is universally recommended for ages 6 months and above, we mean it, says Dr. Conway. The only group that should absolutely not get it again would be somebody with a genuine allergic reaction to the vaccine obviously, they should avoid it.
Older people and people with underlying conditions should really even be higher priority than others to get the flu vaccine, says Dean Winslow, MD, an infectious disease specialist and professor of medicine at Stanford University School of Medicine in California.
The fact is, the flu can be much more disastrous for these high-risk populations.
People with asthma, heart disease, diabetes, and a number of other chronic health conditions are at a higher risk of developing serious flu complications that can result in hospitalization or even death, per the CDC.
Indeed, during recent flu seasons, 9 out of 10 people hospitalized with the flu had at least one underlying health condition, the agency notes.
Being pregnant also puts you at an increased risk of more severe illness from the flu. This is due to changes in the immune system, heart, and lungs that occur during pregnancy .
The flu vaccine offers protection against the flu to both the mother and the baby.
Why Do Some People Not Feel Well After Getting A Flu Shot
Flu vaccine side effects are generally mild and go away on their own within a few days. Some side effects that may occur from a flu shot include soreness, redness, and/or swelling where the shot was given, headache , fever, nausea, muscle aches, and fatigue. The flu shot, like other injections, can occasionally cause fainting.
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Does The Flu Shot Cause Flu
Flu shots contain killed, or inactivated, flu viruses. They are not able to cause flu. These viruses activate the immune system to create proteins called antibodies.
The body stores antibodies and can use them to fight off future flu infections.
As a result, a person might be able to avoid flu completely after receiving the shot, or if they do catch flu, it is more likely to be a mild illness.
The flu shot can cause symptoms similar to those of flu, such as a headache or nausea, but it cannot give the person flu. Learn more here.
Who Can Get A Free Flu Vaccine

You can get a free flu vaccine if you are:
- aged 50 to 64 years
- living in a nursing home or other long-term care facility
- in regular contact with pigs, poultry or waterfowl
People aged 50 to 64 have been added to the free flu vaccine programme until the end of April 2022.
People with these conditions can also get a free flu vaccine:
- chronic heart disease, including acute coronary syndrome
- chronic liver disease
- chronic kidney failure
- chronic respiratory disease, including chronic obstructive pulmonary disease , cystic fibrosis, moderate or severe asthma, or bronchopulmonary dysplasia
- chronic neurological disease including multiple sclerosis, hereditary and degenerative disorders of the central nervous system
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Redness Or Swelling At The Injection Site
Anytime you pierce the skin and put something into the body it can cause a topical reaction, says Dr. Adalja. This is just a sign that your immune system is activating.
But this redness and swelling where you get your shot is a common side effect that only typically lasts a few days. Itll go away on its own, but if its really bugging you, you can take ibuprofen or acetominophen .
What About People Who Get A Seasonal Flu Vaccine And Still Get Sick With Flu Symptoms
There are several reasons why someone might get flu symptoms, even after they have been vaccinated against flu.
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Can Severe Problems Occur
Life-threatening allergic reactions to flu shots are very rare. Signs of serious allergic reaction can include breathing problems, hoarseness or wheezing, hives, paleness, weakness, a fast heartbeat, or dizziness. If they do occur, it is usually within a few minutes to a few hours after receiving the shot. These reactions can occur among persons who are allergic to something that is in the vaccine, such as egg protein or other ingredients. While severe reactions are uncommon, you should let your doctor, nurse, clinic, or pharmacist know if you have a history of allergy or severe reaction to influenza vaccine or any part of flu vaccine.
There is a small possibility that flu vaccine could be associated with Guillain-Barré syndrome, generally no more than 1 or 2 cases per million people vaccinated. This is much lower than the risk of severe complications from flu, which can be prevented by flu vaccine.
Special Consideration Regarding Egg Allergy
People with egg allergies can receive any licensed, recommended age-appropriate influenza vaccine that is otherwise appropriate. People who have a history of severe egg allergy should be vaccinated in a medical setting, supervised by a health care provider who is able to recognize and manage severe allergic reactions. Two completely egg-free flu vaccine options are available: quadrivalent recombinant vaccine and quadrivalent cell-based vaccine.
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Flu Shot Vs Covid Vaccines
Since the COVID-19 vaccines started rolling out in December 2020, over 67% of the U.S. population have received at least one dose. Some people reported side effects of the COVID shot that kept them home in bed for a day or two.
While the COVID vaccine does not protect against the flu the side effects of the vaccines are similar. A sore arm where the shot was given, fatigue, fever, and body aches, can happen with either vaccine.
It’s also completely safe to get both shots at the same time. The Centers for Disease Control and Prevention has given the green light for people to get both a COVID-19 vaccine and the flu shot, along with other vaccines that they might be due for, at the same visit.
According to the CDC, the immune response that is triggered after you get a vaccine is usually the same whether you get one shot at a time or multiple shots at once.
Does The Flu Shot Cause Autism
Some people have concerns that the flu vaccine, and other vaccinations, can cause autism.
However, according to the CDC , studies have shown that there is no link between vaccination and autism.
There are many other myths circulating about vaccinations, including the notion that they weaken the immune system, give people flu, or contain unsafe toxins. These claims are not based on scientific evidence.
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Can The Moderna Booster Protect Against Omicron
So far, so good.
According to research by Imperial College London, booster vaccines are 80% effective against the Omicron variant. However, this study was conducted specifically with Pfizer boosters. Imperial scientists also say that Omicron variant-specific vaccines are likely to be required to stop infections.
Today Moderna released some specific data about how well their vaccine works.
According to the stats, a booster dose of 50 micrograms increases protection 37 times above the level of antibodies that were there with a double-dose. On the other hand, a 100 microgram dose pushes that protection up 83 times what it already was. Right now, this data still needs to be peer-reviewed, but it remains quite hopeful.
For reference, both initial shots of Moderna are 100 micrograms each.
The company are working on a vaccine that targets Omicron, with clinical trials set to begin in early 2022. For now, only real-world data can explain if the vaccine can protect people throughout the winter.
The dramatic increase in COVID-19 cases from the Omicron variant is concerning to all. said Stéphane Bancel, Moderna CEO.