The governor said 98% of Californians are currently under the three-week stay home order due to plunging ICU availability.
RELATED: What happens when California's ICU capacity reaches 0%? Gov. Gavin Newsom explains
The San Joaquin Valley was the first region to face the restrictions, and the order was initially going to expire December 28. Southern California's stay home order was set to expire December 30. Both areas have seen 0.0% ICU available ICU capacity for several days in a row.
"Based upon all the data, and based upon all these trend lines, it's very likely based on those current trends that we'll need to extend that stay at home," Newsom said.
California's Health and Human Services Secretary Dr. Mark Ghaly said the state will be looking at ICU projections for four weeks after the regional stay home order would be lifted to ultimately determine whether or not restrictions will remain. Health officials will also monitor current ICU capacities, the number of new coronavirus cases and transmission rates.
Newsom said hospitals have also faced staffing issues, and he is expecting the surge in hospitalization and ICU admissions to continue. The federal government has begun deploying healthcare workers to help within hospitals across the state and the alternate care sites that have been activated in California.
MAP: CA counties that can, can't reopen under new rules
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Dr. Ghaly also addressed reports of a new strain of COVID-19 coming out of the United Kingdom, parts of Europe and South Africa.
"(The strain is) a little bit more sticky than the COVID virus that we've been seeing today. And what I mean by that is we know that for COVID to enter a human cell, it needs to bind to a receptor, or sort of front door, or on a human cell and the new mutated COVID virus seems to bind a little tighter a little more easily and enter the cell of the human body easier than our current COVID virus that we have here, primarily in California and the United States," Ghaly said.
"So what does that mean exactly? It means that an exposure to somebody with a new strain may mean you're more likely to get infected than if you were exposed to the current string. And that is why we're worried," he added.
Ghaly said the state's COVID-19 Genome Sequencing Initiative, which monitors the coronavirus for new mutations, has not seen this new strain in California. However, the state is considering travel restrictions for people coming from the UK as a precaution.
Meanwhile, California began vaccinated some healthcare workers last week. Newsom said 70,258 doses were administered. The state is expecting its first shipment of the Moderna vaccine after it was authorized by the FDA this weekend. California will receive 672,600 doses in this first shipment. The state is waiting for another shipment of 233,025 Pfizer vaccines.
California's COVID-19 positivity rate was 12% on Monday, up from 8.7% recorded two weeks ago. Hospitalizations increased 63% over the last 14 days, and ICU rates increased by 51%. Eighty-three people died from COVID-19 across the state in the last 24 hours.
The latest available ICU capacity by region is: