As the coronavirus began pushing the nation into lockdown in March 2020, Joshua Coleman, an anti-vaccine campaigner who organizes anti-vaccine rallies, went on Facebook Live to give his followers a rallying speech. He laid out what he thought the pandemic really was: an opportunity.

“This is the one time in human history where every single human being across this country, possibly across the planet, but especially in this country, are all going to have an interest in vaccination and vaccines,” he said. “So it’s time for us to educate.”

WASHINGTON — Two of the Food and Drug Administration’s top vaccine regulators will leave the agency this fall, a development that could disrupt its work on deciding whether to recommend coronavirus vaccines for children under 12 and booster shots for the general population.