Muhammad Adnan adjusts his mask as he goes through a book at the Hicklebee's store in Downtown Willow Glen, in Santa Clara County, Calif., on June 15, 2021. The father of a three-year-old boy said that he was not comfortable going out without a mask after California's reopening on June 15. (Harika Maddala/Bay City News)

California will restore an indoor mask mandate this week in the wake of a recent increase in COVID-19 cases, one of the state’s top health officials said Monday.

State Health and Human Services Secretary Dr. Mark Ghaly said the state will reimplement an indoor mask requirement, regardless of vaccination status, from Wednesday to Jan. 15.

The state will also tighten the window in which people who are not fully vaccinated can show a negative COVID-19 test result if they want to attend an event with more than 1,000 attendees

Negative rapid antigen tests must be taken within 24 hours of the event while PCR tests must be taken within 48 hours of the event. Previously, a negative test of any kind had to be taken within 72 hours of a large event.

Ghaly said that the recent rise of the omicron variant of the virus and a 47 percent increase in cases statewide since Thanksgiving has led to concern over a possible surge in cases similar to last winter’s surge, when nearly 20,000 state residents died from COVID between the end of December and February.

“We know that we are entering into a pretty hard time and we are starting to see some of these numbers go up in some communities pretty quickly,” Ghaly said.

In addition to the requirements for masks and large events, Ghaly said the state will begin recommending that all people traveling to or from California get tested for the virus within three-to-five days of their arrival.

Most of the state’s most populous areas, including Los Angeles and the Bay Area, have had indoor mask requirements for several weeks since the delta variant first led to a spike in COVID-19 cases, hospitalizations and deaths in August.

Ghaly said Monday that the new mask mandate will affect roughly half of the state’s population who live in an area that does not currently require masks in indoor public spaces, regardless of vaccination status.

Indoor mask requirements have remained in full effect for unvaccinated people since the state reopened in June.

“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,” to prevent the virus’ spread.

Individual venues, stores and other indoor public spaces will continue to be responsible for enforcing the mask rules, according to Ghaly, who said he hopes that people who enter indoor public spaces over the next month do so with the expectation that they will be required to wear a mask or other face covering.

While previous statewide mask requirements have been more broad, applying to both public and private spaces and even outdoors, Ghaly said Monday that the month-long mandate will only apply to public areas like grocery stores.

That said, Ghaly did advise residents who have yet to do so to get vaccinated if they plan to hold or attend holiday gatherings with family and friends and to take precautions that will reduce the risk of transmission like opening windows to increase air flow.

The state is also not planning to reimplement restrictions on certain businesses like it did prior to June 15, when the state’s color-coded reopening system was lifted.

“I know a lot of people say, ‘is this the first step along the course that we’re familiar with, other closures and other things?’ Absolutely not,” Ghaly said. “We have seen (masks) help us keep things going and thriving. … We believe we can do that again.”