UMass Boston announced Friday that masks will be required in all campus buildings and buses - and large outdoor gatherings - starting Monday.

In e-mail to the campus community, university officials pointed to the Center for Disease Control and Prevention's decision to shift Suffolk County from "medium" to "high" risk of Covid-19 transmission.

Robert Pomales, executive director of UMass health services, and Marie Bowen, vice chancellor for human resources, wrote:

"While on-campus transmission has remained low and our very highly vaccinated population continues to have strong protection against severe disease, we nonetheless will continue to follow the CDC guidance. UMass Boston will reinstitute our indoor mask requirement on Monday, January 9. 

"Our mask requirement applies to all individuals regardless of vaccination status and the requirement applies in all indoor settings (including campus shuttles) as well as in crowded outdoor settings. "

The school says it has free masks available at four locations, along with free testing and vaccinations.