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.