09/02/2026
FLU FACTS OF THE WEEK:
MYTH: "I got the flu shot before and it gave me the flu."
FACT: The flu shot cannot biologically give you influenza. Injectable flu vaccines are made with either inactivated virus or influenza components that cannot cause flu infection. The nasal live-attenuated vaccine can result in respiratory symptoms, but because it is cold-adapted, it multiplies in the nose, eliciting immunity — but not in the lungs, and thus cannot cause influenza (Cleveland Journal of Medicine).
So why do some people feel sick afterward?
Mild soreness, headache, muscle aches, or a low-grade fever can happen after vaccination. These are generally short-lived and are not influenza. It also takes about 2 weeks for your body to develop protection after vaccination, so it's possible to become infected with flu shortly before or after receiving your vaccine. And plenty other respiratory viruses circulate during flu season that can feel a lot like influenza.
"Well, I got my shot and still got the flu later on so it obviously does not work."
No vaccine provides 100% protection but that doesn't mean it isn't working.
How well the flu vaccine works varies from season to season depending on factors such as a person's age and health and which influenza viruses are circulating. Even when vaccination doesn't completely prevent influenza, research shows that it can help reduce the severity of illness and the risk of more serious complications and hospitalization.
Think of the flu vaccine as another layer of protection, not an invisible force field.
Preventing severe illness matters, too!
Learn more:
https://www.cdc.gov/flu/prevention/misconceptions.html
https://www.cdc.gov/flu/vaccines/keyfacts.html
https://www.cdc.gov/flu/vaccine-safety/index.html
https://www.ccjm.org/content/86/12/782/tab-figures-data
