The Food and Drug Administration has announced a major policy shift in how Covid-19 vaccine boosters will be evaluated moving forward. Under the new guidelines, healthy individuals between the ages of six months and 64 without underlying health conditions will face more rigorous standards for vaccine approval, requiring data from randomized, controlled clinical trials that demonstrate actual health outcomes—such as reductions in infection or hospitalization rates—rather than relying solely on antibody response measurements.

This change marks a departure from the previous model, where annual updates to Covid booster shots were approved based on immunogenicity data, mirroring the approach used for influenza vaccines. The updated framework reflects a more targeted strategy, with distinct standards based on patient risk levels. For those at higher risk, including seniors and individuals with preexisting conditions, the FDA will continue to accept immunogenicity as sufficient evidence to support vaccine efficacy.

FDA Commissioner Marty Makary and Vinay Prasad, who now oversees the agency’s vaccine division, outlined the new approach in a paper published in the New England Journal of Medicine. Prasad, known for his critiques of the pharmaceutical industry, played a central role in developing the new criteria. The agency emphasized that while maintaining flexibility for high-risk groups, it would demand “gold-standard” scientific data before extending approvals to the broader, low-risk population.

The policy realignment comes as Health and Human Services Secretary Robert F. Kennedy Jr., a longtime critic of government vaccine policy, leads a broad restructuring of U.S. public health agencies. Under this evolving strategy, manufacturers seeking approval for boosters targeted at healthy Americans will need to meet significantly higher evidence thresholds than in the past.