The Food and Drug Administration has raised the minimum number of young children that should be in Covid-19 vaccine trials to better detect any side effects, people familiar with the matter said.
A big reason for the change, one of the people said, was to look for side effects like the rare heart condition known as myocarditis that surfaced in small numbers of people who took one of the messenger RNA vaccines after they were authorized.
The FDA recently asked Pfizer Inc. and Moderna Inc. to increase the size of their studies in children 5 to 11 years old to at least 3,000, up from 1,000, the people familiar with the request said.
The New York Times reported the change earlier on Monday.
“While we cannot comment on individual interactions with sponsors, we do generally work with sponsors to ensure the number of participants in clinical trials are of adequate size to detect safety signals,” an FDA spokeswoman said.
