U.S. health agencies including the CDC this week canceled meetings with external groups, paused some public health publications and told employees to freeze travel after directives from the Department of Health and Human Services,

The halt has frozen research grants, meetings and key health updates. “Everything is basically in chaos,” said one cancer researcher.

The Trump administration is expected to tap Susan Coller Monarez, the deputy director of a federal health research agency, to serve as the acting head of the Centers for Disease Control and Prevention,