FRIDAY, May 2, 2025 (HealthDay News) — U.S. Health and Human Services Secretary Robert F. Kennedy Jr. plans to change how vaccines are tested in the U.S., a decision that could impact how quickly and widely vaccines are made available.

The Department of Health and Human Services says it will require new vaccines to be tested against a placebo, which could complicate and delay Food and Drug Administration approval of many vaccines.

The top US health department plans to require placebo testing for all vaccines in an effort to offer "straightforward" public health information, but experts say such testing could limit availability and raise ethical concerns.