Why you may feel sick after getting the flu shot

I have a confession to make. I have opted out of getting a flu shot a few times in my adult life. I know this seems irresponsible of me, especially being a health reporter and all.

But I can explain.

It happened almost as a pattern – I’d get a flu shot, and I’d instantly feel sick. Headaches, stuffy nose, a cough, your typical flu symptoms. I’d ask myself: What was the point of getting the flu shot?

The years I skipped the influenza vaccine: nothing. It was as if the flu shot made me sick. At least that is what I told myself to ease the guilt.

When flu season comes around and I am assigned to write an influenza-related story, the self-judgment kicks in. I can hear the voice of Kathleen Grassi, director at the Public Health Department, speaking about the importance of getting vaccinated. She is one of my go-to people when covering this topic, and she’ll say something along the lines of: “It’s not too late to get a flu vaccination” or “Getting the flu shot is definitely recommended.”

I write about flu clinics – free shots for everyone! I take the tips, write them up and go on about my day.

So what is the point of me sharing this blunder? Well, I know I am not the only one who at some point erroneously believed that the seasonal flu vaccine can actually cause the flu illness.

But this is impossible, according to the experts.

Dave Fluitt, a pharmacist with Raley’s who often blogs about the flu and vaccinations, said this is a major misconception that pharmacists often deal with.

Information provided by the Centers for Disease Control and Prevention shows that a vaccine is made one of two ways: It can either be made with a flu vaccine virus that has been inactivated and therefore not infectious, or it is made without the virus.

So why do some of us feel sick after getting vaccinated? Fluitt explained that about 30 percent of people will experience coldlike symptoms 24 to 48 hours after getting the flu shot. This is the body mounting an immune response, Fluitt explained.

“But it’s a whole lot better than 2  1/2 weeks of the flu,” Fluitt said.

The pharmacist also explained that it takes about two weeks after vaccination to get immunity. Meaning, it is possible a person can be exposed to the influenza virus shortly after getting vaccinated and consequently become ill with the flu. Symptoms often start about one to four days after the virus has entered the body.

Some may also experience flu-like symptoms because the vaccine didn’t provide adequate protection. This is most common among people with weak immune systems or people 65 and older.

People are asked to get vaccinated annually because the flu virus changes every year. Fluitt estimates that only about 60 percent of people do get vaccinated every year. “There’s definitely room for improvement,” he said.

What people often forget is that the flu is a very serious illness, Fluitt said. It’s not just a really bad cold.

According to the CDC, 200,000 people are hospitalized annually because of the flu.

“It’s very serious; babies and seniors are at higher risk,” Fluitt said.

Fluitt also suggests that people consult with their doctors or pharmacists on vaccine options with higher dosages. A high-dose vaccine may offer more protection than the standard flu shot and is usually recommended for people 65 and older.

While getting vaccinated by October usually offers the most protection, according to the experts, it is never too late.

This story was originally published December 20, 2015 at 11:27 AM with the headline "Why you may feel sick after getting the flu shot."