SACRAMENTO, Calif. (NewsNation Now) — California’s health department said it was safe to immediately continue using a batch of Moderna COVID-19 vaccine doses after officials urged a pause on Sunday due to possible allergic reactions.

Wednesday’s decision frees up more than 300,000 doses to counties, cities and hospitals struggling to obtain supplies. With the largest U.S. population at 40 million people, California has the second-highest coronavirus death toll in the country behind New York, according to Johns Hopkins University.

California Department of Public Health on Sunday urged a pause in the use of a specific lot of the Moderna virus after fewer than 10 people who received shots at a San Diego vaccination site needed medical care, possibly due to rare but severe allergic reactions.

But after a safety review and consultation with Moderna and health agencies, the state “found no scientific basis to continue the pause” and said vaccinations can “immediately resume,” state epidemiologist Dr. Erica Pan said in a statement.

The safety review included discussions with various U.S. authorities, including the U.S. Food and Drug Administration and the U.S. Centers for Disease Control and Prevention, and found no scientific basis to continue the pause.

“These findings should continue to give Californians confidence that vaccines are safe and effective, and that the systems put in place to ensure vaccine safety are rigorous and science-based,” Pan said, adding that some of her family members had received it.

Moderna said on Tuesday it had received a report from the health department that several people at a center in San Diego were treated for possible allergic reactions after vaccination from one lot of its coronavirus vaccine.

Moderna said it is unaware of comparable adverse cases from other vaccination centers that may have administered vaccines from the same batch as the one in the San Diego centre, or from other batches.

The release of the Moderna doses comes as California officials struggle to meet the challenge of vaccinating all those awaiting them, including millions of people 65 and older who recently were made eligible behind health care workers and people in nursing care homes.

Large California counties have been opening up more mass vaccination sites as they struggle with unprecedented demand.

Providers place vaccine orders, and the state reviews and submits them to the federal government, which can authorize and submit the request to the manufacturer. Counties have complained about lags and unpredictable distribution.

More than 4 million doses had been shipped and about 1.5 million had been administered as of Tuesday, according to state public health department figures. Health officials have said the delay may be due in part to some doses not actually having arrived in the state yet.

With the all-clear for Moderna’s vaccine, San Francisco will be able to use 8,000 doses it had put on hold and no longer expects to run out of vaccine on Thursday as previously feared, the San Francisco Chronicle reported. Health officials had received fewer than 2,000 additional doses this week for city hospitals and community clinics.

Even so, the city hopes to vaccinate an estimated 900,000 people who live or work there by June 30, although it would have to double or triple its vaccination rate to 10,000 a day.

“The chief obstacle we are facing is not enough doses,” said Roland Pickens, director of San Francisco’s public health care system, at a supervisors’ hearing Wednesday. “You only get it one way; you get it for free and you get it from the federal government.”

Los Angeles County, with a quarter of the state’s population, was straightening out problems with online and call-in systems that residents over 65 can use to make a vaccination reservation, said Barbara Ferrer, director of the county Department of Public Health.

But the real problem was supply. Ferrer said more than 70% of doses received for next week are already earmarked for second shots.

Former Gov. Arnold Schwarzenegger put in a vaccination pitch, posting a Twitter video of himself getting a shot in his bicep at Dodger Stadium’s drive-thru site.

“Today was a good day,” he wrote. “I have never been happier to wait in a line. If you’re eligible, join me and sign up to get your vaccine. Come with me if you want to live!”

The Associated Press and Reuters contributed to this article: Reporting by Don Thompson/AP; Bhargav Acharya/Reuters and Sabahatjahan Contractor/Reuters.