A box of Pfizer's COVID-19 vaccine, which must be stored at ultra-cold temperatures. (Photo via Province of British Columbia/Flickr)

Two sub-zero freezers slated to store thousands of doses of the Pfizer vaccine for COVID-19 have arrived in San Mateo County, county officials said Wednesday.

The freezers at San Mateo Medical Center will store allotments for the county’s health department and for Seton Medical Center, and vaccines for other acute hospitals will be shipped directly to the respective hospitals.

“These freezers are a really big deal only when we look at the Pfizer vaccine because it needs to be stored at -70 degrees while the Moderna vaccine just needs to be freezing,” Dr. Anand Chabra, county COVID-19 mass vaccination section chief and Family Health Services medical director, said. “Because of its formulation, in order to be viable it needs to be stored this way and the other thing is that there are no preservatives in there.”

County hospitals may start vaccinations as early as Thursday, as the county has already received its first allotment of 5,850 Pfizer vaccines on Tuesday.

By next week, the county is expecting and additional 5,850 Pfizer vaccines and 7300 Moderna vaccines pending federal approval.

“This first batch is purely for the acute hospital health care workers,” County Family Services Director Lizelle Lirio de Luna said. “Next week will be for other priority groups such as long-term care facilities, medical emergency responders, public health staff working as vaccinators.”

By the end of the month, the county expects to have a total of 24,000-30,000 vaccines of both Pfizer and Moderna.

The total December allotment would provide the first dose for about 24,000 of the county’s 38,000 health care workers who comprise the first priority group — not all health care workers in the county.

Both the Moderna and Pfizer vaccines require two doses for full efficacy. The second dose of Pfizer vaccine is required to be given after 21 days of initial dose and the Moderna vaccine is 28 days.

“The first-tier priority could include people who are doing direct clinical care, people who are in contact with those who are COVID-positive, janitors, people who are transporting patients,” de Luna said.

Health care workers not included in the count include federally qualified health clinics, lab technicians, dentists, primary care providers, and specialty doctors among others.

The prioritization is set by the state and federal government.

“We also really want to focus on staff and residents at skilled nursing facilities because that is an incredibly vulnerable population,” de Luna said.

There are about 8,000 residents in skilled nursing facilities. Some of their vaccinations would be headed by hospitals that have their own skilled nursing facility.

The other skilled nursing facilities that are not connected with a hospital will receive vaccinations through a partnership between the state and pharmacies at local Walgreens and CVS locations. The partnership is expected to be approved by the end of the month.

This means that county residents could also go to their local Walgreens or CVS to get a vaccine like they would a flu shot, once the vaccine is open to the public.

“That partnership makes it easier on the county but also provides free flu shots to those who may struggle to get access like uninsured or undocumented individuals,” de Luna said.

Once vaccination is complete for skilled nursing facilities and frontline staff at acute hospitals, the next phase will focus on “essential workers.”

“The next allocation is described by the state as essential workers, but we haven’t received a definition for that,” de Luna said. “So, all the details are still being worked out.”

And while the arrival of vaccines provides some hope, it will likely take months for all the county residents who want a vaccine to get one.

“As we see more people getting vaccinated and case numbers going down, we can expect the state to also reduce restrictions and slowly return to normal,” Chabra said. “We are following the state’s protocols.”

In the meantime, county officials are pleading with residents to continue staying home, socially distancing and follow other coronavirus safety protocols to curb the case count and protect hospital intensive care unit capacity.