Just a month ago, Los Angeles County and the rest of California celebrated a long-awaited reopening, marking the tremendous progress made in the battle against COVID-19 by lifting virtually all restrictions on businesses and other public spaces. Now, the coronavirus is resurgent, and the nation’s most-populous county is scrambling to beat back the pandemic’s latest charge.

Starting Saturday night, residents will again be required to wear masks in indoor public spaces, regardless of their vaccination status.

The latest order not only puts the county further at odds with both the California Department of Public Health and the U.S. Centers for Disease Control and Prevention — both of which continue to maintain that vaccinated people need not cover their faces indoors — but puts officials in the precarious position of asking the inoculated to forfeit one of the benefits recently enjoyed.

“This is an all-hands-on-deck moment,” said Dr. Muntu Davis, the county’s health officer.