Boise State University isn’t going back to a mask mandate for fall.

But the state’s largest university is urging students and staff to mask up.

“Boise State University is strongly advising all members of our campus community — regardless of vaccination status — to wear a facial covering when indoors on campus,” the university said in an email to the campus community Wednesday. “Although ongoing research confirms that COVID vaccines are safe and effective, it is possible for fully vaccinated individuals to unknowingly spread the virus to unvaccinated individuals.”

Boise State’s new guidance came one day after the Centers for Disease Control and Prevention did an about-face on its back-to-school recommendations.

The CDC now urges mask usage, in schools and other indoor venues, whether people are vaccinated or not. These new guidelines apply to communities with high or substantial coronavirus case rates, and Ada County is among 28 Idaho counties under that heading.

“The university is monitoring the situation closely and will issue additional guidance as warranted by changing infection rates or modified federal, state or local guidelines,” Boise State said Wednesday.

Meanwhile, Boise State is encouraging students and staff to get a COVID-19 vaccine. Idaho’s public universities cannot require a vaccine; they can only urge vaccinations.

According to a Boise State internal survey, university vaccination rates exceed Ada County’s rates. In all, 67 percent of Boise State’s faculty, students and staff are voluntarily fully vaccinated. Rates range from 90 percent for faculty to 56 percent for students.

According to the Department of Health of Welfare, 56 percent of Ada County residents are fully vaccinated.