Five Myths About the Flu Shot

Doctor rubbing down patient's arm with alcohol swab

A flu shot is important not just for an individual's health but also to protect others from infection.

According to the Centers for Disease Control, flu activity has been higher than normal in the US this season, which typically lasts from October until April or May. It’s more important than ever for people to get vaccinated, but many still have misconceptions about the flu vaccine and downplay its benefits.

We asked MSK infectious disease specialist Monika Shah to debunk common myths about the vaccine.

Myth 1: If the flu shot is not 100% effective, there is no point in getting it.

It’s true that the vaccine is not 100% effective, but studies show that among the overall population, vaccination reduces the risk of flu illness by between 40% and 60%. Even partial effectiveness is still very important.

“Having partial immunity can reduce the severity of symptoms if you do become infected,” Dr. Shah says. “And getting vaccinated protects those around you, including those who are more vulnerable to serious flu illness, including children, elderly adults, and people with cancer.”

Myth 2: The flu shot could give me the flu.

You cannot get influenza from the flu shot. “The flu vaccines given today are either made from an inactivated (killed) form of the influenza virus or from very specific genetic pieces of the flu virus,” Dr. Shah says. “None of the injectable vaccines can cause infection and illness.” There are forms of the vaccine given through the nose that contain weakened forms of the live virus, but they are no longer widely used. This form should not be used in anyone with a weakened immune system.

“People sometimes get sick from another virus around the time they receive the flu shot, and they mistakenly attribute this to the vaccine,” she explains. The only effects of the current flu shot are usually soreness at the injection site, minor aches, and occasionally a low-grade fever.

Because the strains may change from year to year, a person should be vaccinated annually.
Monika Shah infectious disease specialist

Myth 3: I don’t need the flu shot every year.

Influenza viruses change from year to year. Public health experts make their best judgment about which strains pose the biggest threat, and the vaccines are engineered accordingly. “The best we can do is have a vaccine that targets what we think are going to be the circulating strains,” Dr. Shah says. “Because the strains may change from year to year, a person should be vaccinated annually.” In addition, a person’s immune protection from the vaccination declines over time, so annual vaccination is needed to provide the strongest protection.

Myth 4: I don’t need the flu shot if I wear a mask when I’m around other people.

“People can get the flu when a sick person coughs or sneezes or even talks because the virus travels in the air, but often they can just as easily get it after touching surfaces that have been contaminated,” Dr. Shah says. “Then they unconsciously touch their face, and the virus comes in through the mouth or eyes. It usually doesn’t happen because someone coughed right in their face.”

While wearing a mask could theoretically prevent some cases of the flu, it is far more effective to wash your hands frequently. “You don’t need to use anything special — soap and water is fine or a hand sanitizer if you don’t have access to that,” Dr. Shah says. “It’s also important to keep shared spaces clean, so if there is a sick person around you, wiping down desks, countertops, doorknobs, and other shared surfaces with a disinfectant is important.”

Myth 5: If I already had the flu this season, I don’t need the shot.

Someone who had the flu can still get sick again during the same season. The vaccine does not protect against every strain of the influenza virus. “The strains can be very different from one another, and the way that your immune system sees them is different,” Dr. Shah says. “The second case of flu can be just as severe as the first, and you could suffer from other complications, such as pneumonia.”

People should not skip the vaccine because they think it’s “too late” in the season. “Flu season can last as late as May, so most people should get the shot up through then if they have not yet been vaccinated,” Dr. Shah says.