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.

A Department of Health and Human Services spokesperson called the move "a radical departure from past practices."

The HHS is set to require placebo tests for all vaccines moving forward. Kennedy is one of about 50,000 Americans who have spasmodic dysphonia. It may be time to add a handful of this nut to your daily snack rotation.