Key US infectious disease researchers have been barred from directly communicating with the World Health Organization during ongoing virus outbreaks, according to sources and internal Health and Human Services agency communication.

The restrictions to staff at the agency once led by Dr. Anthony Fauci were in place when hantavirus infections first broke out. Staff could participate in WHO meetings after Ebola outbreaks intensified, but in listen-only mode.

Multiple top health positions remain vacant as the restrictions limit cooperation with global counterparts during public health emergencies.

AI-generated summary was reviewed by a CNN editor.

Key officials responsible for leading US research on infectious disease threats have been barred from speaking directly with the World Health Organization — effectively shutting some of them out of the global discussions on virus outbreaks, according to documents and multiple sources who spoke to CNN.