Moderna Inc. has agreed to do a placebo-controlled trial of its new Covid vaccine that was recently approved by US regulators, Health and Human Services Secretary Robert F. Kennedy Jr. said Tuesday.

Lakshmi Panagiotakopoulos said she could no longer help vulnerable people after officials removed recommendations to immunize children and pregnant women.

A top coronavirus vaccine adviser to the Centers for Disease Control and Prevention (CDC) resigned from the agency, citing concerns that she would no longer be able to help the most vulnerable