By Anna Giles

SACRAMENTO (CBS13) — As vaccine eligibility expands, demand for appointments is already surging. But will supply keep up?

Some county health officers said they’re getting an increase in doses, but distribution from the state is erratic and unpredictable.

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California just opened the door for people with pre-existing conditions, which also opened the door for more doses.

In Yuba County, County Spokesperson Russ Brown said, “We saw an increase in doses that allowed us to address more in our community. We are considered a somewhat underserved community.”

Brown said the county is preparing for its largest vaccine clinic yet this weekend. They’ll have 1,400 doses to administer.

But it’s a different story in Solano County where health officials are trying to keep up with their own mass vaccination clinics.

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“For the past month, we’ve been receiving far less vaccine than we were prior to that and clearly the state has redistributed vaccine in a way that’s very hard to make sense of,” said Dr. Bela Matyas, the Solano County Health Officer.

Dr. Matyas said Solano County is near the bottom of the state’s list for dose allotments per capita. Earlier this month, Gov.  Newsom vowed to distribute doses to clinics in California’s poorest zip codes — Solano County has four of them.

“So how is it possible for us to have several zip codes that means we should be getting more vaccine, not less and we’re getting way less vaccine. I can’t even begin to suggest that there’s any logic to it,” Dr. Matyas said.

Many people are interested in the one-and-done option with the single-dose Johnson and Johnson vaccine, but it’s the hardest to get a hold of. Most counties have only had one shipment and they say they’re giving to those most in need.

“It made sense for our foothill communities. They have a hard time getting down the hill, sometimes older residents, so they can get the one shot and they’re done and now we’re using with some of our homeless residents,” Brown said.

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Solano County is one of the only areas in Northern California that has opened up vaccines to anyone 50 years or older. They did this despite their limited supply as a way to guarantee all appointments are filled at mass vaccination sites.