CDC’s Influenza Vaccine Effectiveness Networks

In the United States, CDC and the Advisory Committee on Immunization Practices (ACIP) recommend annual influenza (flu) vaccination for all people 6 months and older. Monitoring the performance of flu vaccines is important for understanding and improving the benefits of flu vaccination. Over the past few years, CDC has conducted VE studies using multiple networks, including the U.S. Flu VE Network, Investigating Respiratory Viruses in the Acutely Ill (IVY) Network, the National Vaccine Surveillance Network (NVSN), and the VISION VE Network. The Hospitalized Adult Influenza Vaccine Effectiveness Network (HAIVEN) was previously used to estimate VE among hospitalized adults but it ended enrollment on July 31, 2021, and is no longer being used. CDC continues to collect information on adults hospitalized with flu through IVY and VISION. Additional studies evaluating VE include the Respiratory Virus Transmission Network (RVTN) and the Randomized Assessment of Influenza Vaccine Efficacy Network (RAIVEN).

Some flu vaccine effectiveness networks are also used to evaluate the effectiveness of other vaccines, including COVID-19 vaccines. Those data can be found online.