What to know
The Randomized Assessment of Influenza Vaccine Efficacy Network (RAIVEN) is a research collaboration between CDC, Westat, and multiple sites in the United States to conduct randomized trials to evaluate how well different influenza (flu) vaccines protect people 18-64 years old against flu. RAIVEN uses innovative research methods to make flu clinical trials more accessible to US communities, with a focus on including populations that have been under-represented in vaccine trials in the past.
RAIVEN Trials
During fall 2022, RAIVEN launched a trial to compare the protection against flu from the recombinant flu vaccine versus a standard dose egg-based flu vaccine among people 18-64 years old (NCT05514002). Both vaccines are licensed for people in this age group in the United States. Participants in the trial will be randomly assigned to receive one of the two study vaccines as part of the study and will be monitored for flu virus infections throughout the flu season. The purpose of randomly assigning participants to receive a specific vaccine is to reduce differences between the participant groups who receive the two study vaccines to allow for a more valid comparison of flu illness rates and other outcomes between the two group. The trial will enroll and follow participants during at least two flu seasons (the 2022-23 and 2023-24 seasons).
Flu Vaccine Efficacy and Effectiveness
Measuring flu vaccine efficacy and vaccine effectiveness (VE) are important to better understand how well flu vaccines protect against flu. Vaccine efficacy refers to how well vaccines protect people against infection in clinical trial research studies that randomly assign participants to receive specific vaccines. Vaccine effectiveness refers to how well vaccines protect people in real-world studies in which vaccines are not randomly assigned to people.
CDC measures VE each year to evaluate the benefits of flu vaccines in different age groups and against different clinical outcomes. The RAIVEN study will complement these VE estimates by comparing the efficacy of two types of licensed flu vaccines: standard-dose egg-based influenza vaccines and the recombinant influenza vaccine. These efforts aim to provide data to inform US vaccine recommendations aimed at providing the best protection from flu and its potentially serious complications.
Study Sites
Participating RAIVEN study sites are located in 7 states
- Arizona
- Florida
- Illinois
- New Jersey
- Texas
- Virginia
- Utah
Other Information on CDC Vaccine Effectiveness (VE) Estimates
- More information about how CDC's VE studies are conducted and how to interpret results, is available at How Flu Vaccine Effectiveness and Efficacy are Measures: Questions and Answers for Health Professionals.
- Seasonal Influenza Vaccine Effectiveness provides tables that show the overall adjusted VE and related references for each season starting in 2004-05.