The leading vaccine regulator at the Food and Drug Administration (FDA) has announced a far stricter course for federal vaccine approvals, following claims from his team that Covid vaccines were linked to the deaths of at least 10 children.

Experts suggest the announcement will make the vaccine approval process significantly more difficult.

Dr Vinay Prasad, whose vaccine policy direction has been supported by the US health secretary, Robert F Kennedy Jr, told FDA staff that the agency would rethink its approach to vaccination programs, according to an internal agency email circulated on Friday and later obtained by several media outlets.

The internal memo reportedly stated that a recent review determined at least 10 children had died “after and because of” receiving a Covid vaccine. Prasad noted that these deaths appeared tied to myocarditis, or inflammation of the heart muscle.

A PBS NewsHour correspondent first reported on the memo’s contents in a post on X. The New York Times noted that the document did not include identifying details such as the children’s ages, any existing health conditions, or how the causal relationship between vaccination and death was determined. The vaccine manufacturers involved were also not named.