Flu Vaccines Work
While flu vaccine effectiveness can vary from season to season, every year flu vaccines provide important protections against flu.
CDC calculates flu vaccine effectiveness (VE) each season for multiple reasons.
CDC measures flu vaccine effectiveness (VE) to determine how well flu vaccines work.
CDC uses four networks to estimate vaccine effectiveness: the U.S. Flu VE Network, the Influenza Vaccine Effectiveness in the Critically Ill (IVY), the National Vaccine Surveillance Network (NVSN), and the VISION VE Network.
CDC conducts studies to measure the benefits of seasonal flu vaccination each flu season to help determine how well flu vaccines are working.
CDC estimates the burden of flu and the impact of annual flu vaccination in the U.S using a model that estimates the numbers of flu illnesses, medical visits and hospitalization prevented by vaccination.