SACRAMENTO, Calif., Dec 13 (Reuters) - California will impose a statewide mask mandate in all indoor public spaces as COVID-19 case rates soar, the state"s senior government health official said on Monday as precautions ramp up against the Omicron variant. The mandate, which will take effect on Wednesday and last a month, is one of several measures the most-populous U.S. state is taking to slow a wave of infections that is already straining hospitals in areas where vaccination rates are low. "We know people are tired, and hungry for normalcy," state Health and Human Services Secretary Mark Ghaly said in a conference call with reporters. "Frankly I am, too." The rate of COVID-19 infections in California has jumped 47% since Thanksgiving to more than 14 cases per 100,000 people, Ghaly said. The United States on Sunday reached 800,000 coronavirus-related deaths, a Reuters tally showed, as the nation braces for a potential surge in infections because of more time spent indoors with winter holidays and colder weather, and the highly transmissible Omicron variant. read more In the UK, at least one person has died after contracting the Omicron variant, which now accounts for 44% of new infections in London, officials said. read more California is also tightening testing requirements for unvaccinated people who want to attend large events such as music festivals and professional ball games where more than 1,000 people are in attendance. When the tighter requirements are in effect, people wishing to enter such venues must either prove they are vaccinated or show they tested negative to a COVID-19 antigen test within one day of the event, or a PCR test within two days. The state is also recommending that all travelers to the state be tested for COVID-19 within three to five days of arrival, Ghaly said. The moves are meant to help California avert the need for more draconian measures such as limiting capacity in public places or shutting down parts of the economy. Such rules are not currently under consideration, and officials hope they will not be needed if residents comply with the mask rule, Ghaly said.