WASHINGTON — Americans must recommit to wearing masks and taking other COVID-19 mitigation measures to avoid a new surge of the virus in the U.S., a top health official said Monday.

Rochelle Walensky, director of the Centers for Disease Control and Prevention, said cases have begun to rise slightly again, while hospital admissions remain stable and deaths continue to decline. Variants, which are in some cases more contagious or more dangerous, continue to spread, she said.