The University of Colorado Boulder, Front Range Community College and Naropa University will require masks in indoor public spaces starting this week, the higher education institutions announced Tuesday.

CU Boulder, Front Range and Naropa all cited the spread of the COVID-19 delta variant for the decision to require masks.

The delta variant spreads faster and causes more infections than earlier forms of COVID-19, according to the Centers for Disease Control and Prevention. It can also infect people who have been vaccinated, though the vaccine lessens the likelihood of severe illness, hospitalization and death.

The campus announcements came one day after the Boulder County Board of Health unanimously approved the decision to mandate masks for all students and staff members in all K-12 schools or at child care facilities, regardless of vaccination status. The order went into effect Tuesday.

CU Boulder’s mask requirement goes into effect on Friday. Front Range and Naropa began requiring masks immediately.

In a virtual campus Q&A, CU Boulder Chief Operating Officer Patrick O’Rourke said the decision to require masks was done to make sure the campus could maintain its plans for a more normal fall semester, without shifts to remote learning or capacity restrictions. The mask mandate is hopefully temporary, O’Rourke said.

CU Boulder and Naropa are requiring students, faculty and staff to receive the coronavirus vaccine or request an exemption before the start of the semester.

Front Range Community College is not requiring students, faculty or staff to be vaccinated.

President Andy Dorsey said the decision to not require vaccines is based on the fact that the college does not having students who live on campus and also the history of community colleges as open-access institutions. Approximately 74% of the student body is currently vaccinated, Dorsey said. The college does not have vaccination rates for employees, but Dorsey said he estimates that more than 85% have been inoculated.