Hospitalized Adult Influenza Vaccine Effectiveness Network (HAIVEN)
The Hospitalized Adult Influenza Vaccine Effectiveness Network (HAIVEN) was created to estimate how well the flu vaccine works at preventing severe influenza illness, especially among older adults.
VE in older adults is important to know because this age group has the highest hospitalization rates compared to other age groups. Also, adults who are hospitalized may have more underlying conditions and be more frail than older adults enrolled in the Flu VE Network.
In addition to VE data, HAIVEN also provides insight into severe influenza outcomes, such as length of hospital stay and need for intensive care.
HAIVEN is funded by CDC.
Participating sites are located in four states:
HAIVEN uses a test-negative observational study design similar to the US Flu VE Network and collects data at participating hospitals.
- For more information about how CDC’s VE studies are conducted and how to interpret results, see How Flu Vaccine Effectiveness and Efficacy are Measures: Questions and Answers for Health Professionals.
- See Seasonal Influenza Vaccine Effectiveness, 2004-2018 for a table that shows the overall adjusted VE and related references for each season starting in 2015-16.