California will require indoor masking once again starting Wednesday, following a sharp increase in COVID-19 cases since Thanksgiving, health officials announced Monday.

The new mandate will be in effect from Dec. 15 to Jan. 15, Health and Human Services Secretary Dr. Mark Ghaly said in a briefing Monday.

“We know people are tired and hungry for normalcy. Frankly, I am too,” Ghaly said. “That said, this is a critical time where we have a tool that we know has worked and can work.”

The new order comes as the daily COVID-19 case rate has gone up 47% since Thanksgiving. Previously, the number stood at about 9.6 cases per 100,000 people, and as of Monday, it was over 14 cases per 100,000 people.

While masking was previously a recommendation statewide — except in certain indoor spaces like public transit and schools, where it was required — it will now be a requirement in all indoor settings.

Los Angeles and Ventura counties, as well as most of the San Francisco Bay Area, already have their own indoor mask mandates, which were implemented in the summer, but the new order will affect nearly half the state’s population, including San Diego and Orange counties, the Inland Empire, the Central Valley and rural Northern California.

“This increase in case rates is not experienced equally across the state,” Ghaly said. “We have some counties that remain very low — many of the Bay Area counties, L.A. But others are quite high, and we see this in greater percentage in communities and counties where vaccine rates are low.”

The number of Californians hospitalized with the virus has also climbed, halting weeks of mostly steady declines.

Health officials also announced Monday that California is tightening existing testing requirements by ordering unvaccinated people attending indoor events of 1,000 people or more to have a negative test within one or two days, depending on the type of test.

Additionally, the state is recommending travelers who visit or return to California to get tested within five days of arrival.