A meta-analysis of 511 studies on US COVID-19, respiratory syncytial virus (RSV), and influenza vaccines find meaningful protection against severe disease and hospitalization, evidence that can help fill the void in vaccine guidance formerly provided by independent federal review.

The large-scale project, conducted by the Center for Infectious Disease Research and Policy’s (CIDRAP’s) Vaccine Integrity Project (VIP), was published today in the New England Journal of Medicine. CIDRAP, which publishes CIDRAP News, started the VIP to provide science-based information to help people, communities, policymakers, and clinicians make informed vaccine choices.

Contrary to assertions by US Health and Human Services Secretary Robert F. Kennedy Jr., the study shows that “there is absolutely no shortage of data regarding these vaccine products for COVID, flu, and RSV,” co-senior author Caitlin Dugdale, MD, an infectious disease physician at Massachusetts General Hospital, told CIDRAP News. 

“In fact, there’s a sea of data that’s far too big for any one person to try to get through,” she added. “The findings of our review really reaffirm the safety and effectiveness of these vaccines.”

VIP scientists and other experts presented initial findings from their analysis in August. Today’s data represent the group’s final peer-reviewed outcomes, adding to the veracity of their results.

‘Meaningful protection’ against hospitalization, severe disease 

The study includes only data published in 2023-24, since the most recent comprehensive Advisory Committee on Immunization Practices (ACIP) Evidence-to-Recommendations reviews. Because of the anticipated lack of evidence-based guidance historically provided by the Centers for Disease Control and Prevention’s (CDC’s) ACIP each fall, VIP staff began reviewing 511 of 17,263 randomized controlled trials and observational studies in July. 

For comparison, the ACIP typically works on these recommendations for a year or more. “The degree of teamwork involved in this effort is unparalleled with anything else I’ve ever seen or been a part of,” Dugdale said. “It was a tremendous group effort to try to pull all of this together in a short timeframe.”