What are the side effects of this year’s flu shot?
As COVID-19 vaccines continue to dominate the national conversation, it’s time to think about another important jab: your annual flu shot.
Experts say that after the pandemic’s masking, lockdowns and social distancing nearly eliminated influenza in 2020, the virus may roar back this year. That’s why it’s more important than ever to get vaccinated.
The most common side effects include soreness, redness or swelling near the injection site and headache, low-grade fever or body aches. “These are all signs of your body’s immune response working appropriately and will disappear in a day or two,” says Dr. Robert Citronberg, executive medical director of Infectious Disease and Prevention at Advocate Aurora Health.
One important point? If you feel achy or under the weather, it’s not a sign you contracted the illness from the vaccine.
“You absolutely cannot get the flu from the vaccine,” Dr. Citronberg explains. “The injected flu shot is made from a dead virus, and the nasal spray form of the flu vaccine is made from a weakened virus – neither of which can cause illness.”
If you do come down with the flu within days of vaccination, you would have gotten sick anyway, because the shot takes up to two weeks to form protection.
Flu vaccine side effects are generally mild, and issues beyond soreness are uncommon. In fact, the Centers for Disease Control and Prevention cite clinicals studies in which only soreness and redness at the injection site increased in people given a flu shot versus a placebo. People who received an injection of saltwater reported the same rates of body aches, fever, cough, runny nose and sore throat as those who received a flu vaccine.
More serious side effects, such as an allergic reaction or the possibility of developing Guillain-Barre Syndrome, are extremely rare. Symptoms of an allergic reaction, including difficulty breathing or wheezing, facial or throat swelling, hives and an elevated heart rate, usually occur within a few minutes to several hours after vaccination. While they can be life-threatening, effective treatments are readily available.
The relationship between the flu vaccine and Guillain-Barre Syndrome, a rare disorder in which your immune system attacks your nerves, is not clear. According to the CDC, about 80 to 160 cases of GBS are diagnosed in the United States each week, regardless of vaccination, and data about the association between GBS and the flu shot are inconsistent. If an increased risk exists, it is about one or two additional GBS cases per million flu vaccines administered.
If you have already had GBS, you should talk to you doctor before receiving a flu shot. And if you are currently sick – whether or not you have a fever – it’s best to wait until you recover before receiving your vaccine. Otherwise, experts recommend getting your flu shot as soon as possible, ideally before November.
“Getting your shot earlier in the fall gives your body time to build protective antibodies before the flu season kicks into high gear,” says Dr. Citronberg. The shot lasts about six months, so you’ll be protected through the end of flu season in late spring.
If you’re already planning to get a COVID-19 vaccine, including a booster shot, there’s good news: You can get your flu shot at the same time.
According to the CDC, “COVID-19 vaccines may be administered without regard to timing of other vaccines.” This differs from earlier CDC guidance, which initially advised administering a COVID-19 vaccine a minimum of 14 days before or after other vaccinations. That early recommendation, issued out of an abundance of caution, has changed as scientists have learned more about the vaccines, Dr. Citronberg says.
You can schedule flu and COVID-19 shots by logging into LiveWell, through online scheduling or by calling your primary care provider’s office.
About the Author
Brigid Sweeney, health enews contributor, is a media relations manager for Advocate Aurora Health. Previously, she reported for Crain's Chicago Business.