Can a flu shot make you sick? Facts about the virus and prevention

Did you think you had the flu after eating the Thanksgiving potato salad that was left out overnight? Or did you stop getting a flu shot after you finally got the nerve up to get it and got the flu anyway?

Then it’s time to talk some flu truth, especially since Clark County has seen more than 10 times as many hospitalizations from the flu this season as it had at this time last year — along with four deaths.

Flu imposters

Let’s start with what the flu is — and isn’t.

“This is the time of year when people can experience stomach illnesses as well as seasonal influenza. There is a difference,” said Martha Framsted, a spokeswoman for the Nevada Department of Health and Human Services. “Seasonal influenza is primarily a respiratory illness, while gastroenteritis illness (stomach illness) typically presents with vomiting and/or diarrhea.”

In other words, “stomach flu” isn’t actually the flu.

According to the Centers for Disease Control and Prevention, vomiting and diarrhea can sometimes be related to the flu, especially in children, but these are not the primary symptoms of the illness. The primary symptoms are fever, cough, sore throat, runny or stuffy nose, muscle or body aches, headaches and fatigue.

Health authorities say another major misconception is that you can get the flu from the vaccination itself. According to the CDC, flu shots are made with a flu virus that has been killed or with a single gene from the virus to produce a response from the immune system without causing infection.

So why do we all know someone who says they got the flu after getting the shot? There are a few reasons.

“There are multiple viruses circulating that are able to produce flu-like symptoms” that aren’t the flu, said Dr. Fermin Leguen, acting chief health officer for the Southern Nevada Health District. The flu vaccine won’t protect against these other viruses, such as the rhinoviruses associated with the common cold.

Bad matchmaking

In some flu seasons, the vaccines are less effective than in others. That’s because the vaccines are developed before the season based on the best forecasts of which strains will be circulating.

“During years when the flu vaccine is not well matched to circulating influenza viruses, it is possible that little or no benefit from flu vaccination may be observed,” according to the CDC.

It’s worth noting that so far this year, according to Framsted, the flu vaccine has been well matched to the flu viruses circulating.

“During years when there is a good match between the flu vaccine and circulating viruses,” states the CDC, “it is possible to measure substantial benefits from flu vaccination in terms of preventing flu illness and complications.”

The benefits? “During 2017-2018, flu vaccination prevented an estimated 7.1 million influenza illnesses, 3.7 million influenza-associated medical visits, 109,000 influenza-associated hospitalizations, and 8,000 influenza-associated deaths,” according to the CDC.

During the last flu season, in Clark County alone there were 968 flu-related hospitalizations, and 39 people died, including three children, according to the health district. Government health agencies recommend flu vaccination for everyone 6 months and older, with few exceptions.

Individuals also may get a case of the flu after receiving the flu shot if they were exposed to the virus in the days leading up to immunization or before immunity from the vaccine has taken hold, which takes about two weeks.

And what about those people who say they don’t need the flu shot because they never get the flu?

“I still recommend it to them,” said Dr. Girisha Kaur with Southwest Medical Associates. “Are they around little children? Are they around older adults, 65 and older? Those groups are at higher risk of getting the flu.”

“If we protect ourselves by vaccinating against the flu,” she said, “we’re protecting them, as well.”

Contact Mary Hynes at mhynes@reviewjournal.com or 702-383-0336. Follow @MaryHynes1 on Twitter.