Why do some people think that this year’s flu shot is only 9% effective?
A statement or tweet from the CDC?

Not exactly…
Is This Year’s Flu Shot Only 9% Effective?
As the 2019-20 flu season is just getting started, we don’t actually know how effective this year’s flu vaccine will be…

Early estimates are typically posted in mid-February.
Will we get this year’s flu vaccine effectiveness estimates early because flu season started early?

Will it help that all circulating strains are antigenically similar to the flu virus strains in this year’s flu vaccine?
Or that we are seeing more flu B this year?

We don’t typically talk about flu vaccine effectiveness against flu B strains because they aren’t a big part of our flu seasons, but in general, flu vaccines work well against flu B.
“In general, current flu vaccines tend to work better against influenza B and influenza A(H1N1) viruses and offer lower protection against influenza A(H3N2) viruses.”
Vaccine Effectiveness: How Well Do the Flu Vaccines Work?
In fact, they often work better against flu B than against other strains, so maybe it will turn out to be a good thing if we see more flu B than H3N2 this year…

But most importantly, we know that the flu vaccine has many benefits and few side effects, so even when it isn’t a perfect match it makes sense to get vaccinated and protected.
And know that until we get a better, universal flu vaccine, folks should know that talk about flu vaccine effectiveness is largely academic, as a yearly flu vaccine remains the best way to protect yourself from getting the flu and developing serious complications from the flu.
More on Flu Vaccine Effectiveness
- Is This Year’s Flu Vaccine Working?
- Will This Season’s Flu Shot Fail?
- What Makes the Flu So Deadly?
- Do They Really Just Guess at Which Strain to Put in the Flu Vaccine?
- Do Flu Vaccines Have More Reported Side Effects Than Other Vaccines?
- I’m Not Anti-Vaccine, I Just Don’t Believe in Flu Shots
- Flu Facts vs. Fiction
- Everything You Want to Know About Influenza
- Ask the Experts About Flu Vaccine
- CDC – Frequently Asked Influenza (Flu) Questions: 2019-2020 Season
- CDC – Vaccine Effectiveness: How Well Do the Flu Vaccines Work?