Flu Vaccines Work
While flu vaccine effectiveness can vary from season to season, flu vaccines provide important protections against flu every year.
Learn more about why CDC studies flu vaccine effectiveness (VE) each season.
Learn about how CDC measures flu vaccine effectiveness (VE) to determine how well flu vaccines work.
CDC uses several networks to estimate flu vaccine effectiveness against different flu-related outcomes like medical visits, hospitalizations, and intensive care unit (ICU) admissions.
A table with adjusted vaccine effectiveness estimates for flu seasons from 2004-2024 is available here.
CDC conducts studies each flu season to measure the benefits of seasonal flu vaccination.
CDC estimates the burden of flu and the impact of annual flu vaccination in the United States using a model that estimates the numbers of flu illnesses, medical visits, and hospitalization prevented by vaccination.
