According to the CDC’s Morbidity and Mortality Weekly Report (MMWR), the overall effectiveness of this season’s flu vaccine is an estimated 36%. However, its effectiveness against the season’s dominant strain (Influenza A, H3N2) is estimated at only 25%.
The report, published Feb 16, used data from 4,562 children and adults enrolled in the US Influenza Vaccine Effectiveness Network during November 2, 2017–February 3, 2018.
Highlights from the CDC report include:
- Overall adjusted vaccine effectiveness (VE) against influenza A and influenza B virus infection associated with medically attended ARI was 36%.
- Most (69%) influenza infections were caused by A(H3N2) viruses.
- VE was estimated to be 25% against illness caused by influenza A(H3N2) virus, 67% against A(H1N1) pdm09 viruses, and 42% against influenza B viruses.
According to the CDC, the vaccine is still recommended “because the vaccine can still prevent some infections with currently circulating influenza viruses, which are expected to continue circulating for several weeks.”
The vaccine will still prevent influenza illness and thousands of hospitalizations and deaths, the CDC reports.