KPWHRI contributes to new flu vaccine effectiveness results

Interim data for the 2023-2024 flu season shows that the vaccine has protected all age groups

As one of the sites in the U.S. Influenza Vaccine Effectiveness (Flu VE) network for more than 13 years, Kaiser Permanente Washington Health Research Institute (KPWHRI) conducts research during flu season that helps the CDC (Centers for Disease Control and Prevention) understand the effectiveness of licensed flu vaccines for different age groups and types of influenza.

In February, the CDC published the interim results of that effectiveness research for the 2023-2024 flu season. Senior Investigator Karen Wernli, PhD, is a coauthor on the report, which found that, so far, flu vaccines have substantially reduced the risk of flu-related medical visits and hospitalizations for all age groups. 

“It’s very exciting to see this data showing that the vaccines are doing a good job of protecting people,” said Wernli. “Annual flu vaccination is one of the best ways to avoid getting the flu and to prevent serious complications.”

The data shows that, during this flu season, vaccination has reduced the risk of medical visits by about two-thirds and the risk of hospitalization by about half for vaccinated children. For adults, it has reduced the risk of medical visits by half and the risk of hospitalization by about 40%. The protection against influenza A viruses was similar to the protection in other seasons where the flu vaccine was well matched to the circulating viruses, and the protection against influenza B viruses was higher than in many other seasons. 

The findings are used to help make decisions about what flu strains should be included in vaccinations for the next flu season, as well as the ideal timing of vaccination. More than 20,000 Kaiser Permanente Washington members have participated in the Flu VE study, helping to provide this vital information to policymakers and the public. 

The KPWHRI team has over 80 years of combined experience working on Flu VE research.

Read more in the full report from the CDC.

By Amelia Apfel