Experts have urged Americans to start scheduling their flu vaccinations earlier this year. Last month, NBC News medical correspondent Dr. Natalie Azar stressed that most adults should receive their flu shots in September or by the end of October at the latest. The American Academy of Pediatrics stresses that children should receive flu vaccinations as soon as possible.
“As we continue to face another year of the COVID-19 pandemic, timely influenza vaccination of all persons 6 months of age and older, is a priority this year,” said Dr. Flor M. Munoz, a lead author of the American Academy of Pediatrics' policy statement. “This is particularly important for anyone who has medical conditions that increase the risk for complications for both influenza and COVID-19, including children.”
Some parents, however, are still wary about the flu vaccine. A national survey by Orlando Health from 2015 found that many parents are not only skeptical about flu shots, but more than half of parents surveyed believed that you can get the flu from the vaccine.
In reality, the flu shot can’t and won’t give you the flu, experts stress.
It’s biologically impossible for you to catch the flu from being vaccinated, said Dr. William Schaffner, an infectious disease specialist and a professor of preventive medicine at Vanderbilt University in Nashville.
That’s because the vaccine is constructed from a killed virus. Furthermore, there are only a couple of proteins from that dead virus in the vaccine, so nobody’s getting injected with a complete virus.
Those proteins, taken from the surface of the killed virus, are enough to rev up our immune system and give it a clear target. But they certainly aren’t enough for the flu virus to reconstitute itself in our bodies.
It might be a cold
For the most part, people are mistakenly assuming that symptoms, which coincidentally developed around the time they got the shot, were caused by the vaccine. But, Schaffner explained, just because two events occur around the same time doesn’t mean they’re connected.
“We all know the rooster crows before dawn,” he said. “But we don’t think the rooster makes the sun come up.”
Most of us get our flu shots in the fall, noted Dr. Michael Ison, a professor in the division of infectious diseases at Northwestern University’s Feinberg School of Medicine in Chicago. “That is when rhinoviruses are circulating,” he said. “Most people think a cold is just a stuffy nose. But you can get really sick from a cold. In fact, many viruses can make you as sick as the flu does.”
There’s also the issue of where you get your shot, said Dr. Richard Zimmerman, a professor of family medicine at the University of Pittsburgh. “If you go to the pharmacy or to the doctor’s office," he said, "there’s a good chance someone sitting next to you will be coughing.”
This is not to say you won’t get any symptoms after a flu shot. Here are some side effects people may experience:
About 20% of people experience soreness in the arm that got the shot, said Zimmerman. “That lasts about a day and then goes away,” he said.
“There are a few people who feel a little fatigued after getting the shot,” Schaffner said. “And a few get a headache. These are all part of the body’s immune response to the vaccine. It’s not influenza.”
You already have the virus
If you were exposed to the flu shortly before or after being vaccinated your body didn’t have enough time to strengthen its forces against the virus. The shot doesn’t reach full effectiveness until two to three weeks after vaccination, Ison said.
So, there's no good reason not to get the shot. Even people with egg allergies are now cleared to get it.
“Don’t linger," said Ison. "Run to your health care provider and get vaccinated right away."
This story was updated on September 16, 2021.