Should I Get a Flu Shot?

Everyday Einstein covers the benefits of getting a flu shot this season.

Sabrina Stierwalt, PhD
4-minute read
Episode #210

There are a lot of misconceptions surrounding the science behind flu shots: it’s too late or too early to get one, they don’t work, or even worse, they’ll make you sick. Since flu season is upon us, let’s break down the when, why, and how of who should get a flu shot.

Will the Flu Shot Make You Sick?

The flu shot does not and cannot give you the flu. There are cases of mild, flu-like symptoms occurring as a side effect of the vaccine, but these cases are rare and the symptoms fall far short of the full blown flu. The reason the flu vaccine cannot give you the flu is that the virus contained within the vaccine is either entirely inactive or weakened to the point of ineffectiveness.

The misconception that the flu shot can actually give you the flu likely sticks around because the vaccine typically takes two weeks to start working. If you get the flu shot, but are then exposed to the flu in that two week period before your body has had a chance to full develop the necessary antibodies, you could come down with the flu and blame the shot.

Does the Flu Shot Work?

Another issue is that the flu vaccine is not close to 100% effective, as we have come to expect from other vaccines like those for measles or polio. The effectiveness of the flu vaccine instead hovers around 50% on average. Last year, the vaccine did a bit better, at 63% effectiveness, but two years ago, that fraction dropped to 23%.

This range is due to the fact that the flu virus constantly mutates and comes in many varieties or strains. Each year scientists take an educated guess at what strains will be most prevalent that year and thus which ones should go into the vaccine.

So the flu vaccine is not bulletproof. But if I handed you a card with a 50% chance of avoiding being laid up in bed for a week with the flu, wouldn’t you take it? A fifty-fifty shot is better than no protection at all.

The flu shot also works not just for the person getting it, but for anyone that person comes into contact with. The fewer people out there with the flu, the less flu there is overall, and the more all of us flu-shot receivers can protect those who are at higher risk for flu complications and/or those who were not able to get a flu shot.

The US Center for Disease Control reports that death rates due to the flu have varied between 3,000 to 49,000 per year over the past 30 years. The vast majority (80-90%) of those fatalities were people over the age of 65. Other groups that are at high risk for flu complications include children under four years of age, anyone with cardiovascular or breathing issues (like asthma), those with renal or metabolic disorders (including diabetes), anyone who is immunosuppressed including due to HIV treatment or pregnancy, residents of chronic care facilities like nursing homes, and American Indians or Alaskan natives. These are also the same groups, along with health care personnel, that receive priority in case of a flu vaccine shortage.


About the Author

Sabrina Stierwalt, PhD

Dr Sabrina Stierwalt earned a Ph.D. in Astronomy & Astrophysics from Cornell University and is now a Professor of Physics at Occidental College.

The Quick and Dirty Tips Privacy Notice has been updated to explain how we use cookies, which you accept by continuing to use this website. To withdraw your consent, see Your Choices.