California is set to receive 327,000 doses of the COVID-19 vaccine from Pfizer in the coming weeks, Gov. Gavin Newsom announced Monday.

“That will be California’s portion of the first distribution of vaccines,” Newsom said.

The governor said the vaccines will be “challenging,” because the doses would need to be stored at ultra-low temperatures, and because they require a second dose.

The state had previously announced buying 16 ultra-low temperature freezers to transport Pfizer’s vaccines and dozens more smaller freezers, which will be sent out where they’re needed throughout the state — especially in rural areas.

A plan for how the doses will be distributed is expected this week, according to the governor.

Newsom had said last week that while supplies are scarce, the first phase of the vaccine distribution plan prioritizes health care workers, those in congregate care settings, first responders and other critical infrastructure workers. He said prioritizing those essential workers “shouldn’t surprise anybody.”

“Who are the people we’re prioritizing? It’s one thing to say the health care sector, it’s another to say those that are working in congregate facilities, those working with vulnerable populations,” Newsom said. “But how do you break that down?”

That is being planned by a state committee that meets weekly to develop guidance for the first distribution phase, which targets 2.4 million health care workers in the state. The CDC also has a panel of experts meeting Tuesday to recommend who to vaccinate and when.

Newsom didn’t provide a specific date for when the vaccine doses are expected in California, but said it will be in mid-December.

In November, Pfizer announced that its vaccine appears 95% effective at preventing mild to severe COVID-19 disease and formally asked U.S. regulators to allow its emergency use. California would be getting the 327,000 doses if the Food and Drug Administration does approve of the vaccine.

The company said about 25 million doses may become available in the U.S. in December.

But even with this first batch on the way, Newsom said Californians should follow all the critical non-pharmaceutical interventions to slow the spread of the coronavirus.

“I want to remind everybody that mass vaccination … is unlikely to occur anytime soon,” explaining that that could begin sometime between March and July next year. 

When the timeline for vaccinations is available, the goal is to have it on a state website that’s available for all residents to see, Newsom said.

The U.S. Centers for Diseases Control and Prevention provided California $28 million for vaccine distribution, and the state has already spent $10 million of it on planning with local health jurisdictions.

Newsom said the next round of funding from the CDC needs to be “substantially greater.”