During a visit to Avenal High School in Kings County on Tuesday, Newsom continued his push for more COVID-19 vaccinations and encouraged those who are able to get their booster shots.
California has seen a recent increase in coronavirus cases, making health officials concerned transmission rates will spike more during the holidays.
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Newsom said that as of Monday a little more than 90% of all eligible adults in California had received at least one dose of the vaccine.
"Despite those high vaccination rates, despite those low case rates, those low positivity rates that we've enjoyed over the course of the summer, we are anticipating nonetheless more stress (on California's hospitals) as we go into the fall," Newsom said.
The governor said a surge comes down to two causes, waning immunity to COVID-19 for those who are vaccinated and the number of people who haven't been vaccinated at all.
Newsom said that's why California enacted a new policy last week that expands eligibility for the COVID-19 booster shot.
Anyone in the state who is 18 or older and is six months out from receiving their Pfizer or Moderna shots or two months out from their Johnson & Johnson vaccine can get a booster dose.
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The governor said that areas with low vaccination rates are also seeing the most hospitalizations for COVID-19. That includes Kings County, where only 38% of the county is fully vaccinated.
"They're connected. I was just talking to your health director. 89%-90% of folks that are in the hospital down the road are unvaccinated. This is not complex. This virus is not taking the winter off," Newsom said.