The potential change outlined in a statement would require all new vaccines to undergo placebo testing, sparking concerns among medical experts.

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 said the new plan will promote transparency,

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.