OAKLAND (KPIX) — Just as more Bay Area residents are set to become eligible to receive the COVID vaccine, a new issue with California’s supply of doses related to a recent production problem with the Johnson & Johnson shot has emerged.

California health officials have confirmed the state is expecting a nearly 90% drop in those vaccines next week.

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It’s partly because of a manufacturing mix-up at a facility in Baltimore making one of the components for the J&J shot, impacting some 15 million doses that had to be thrown out.

As KPIX first reported last week, Johnson & Johnson issued a statement saying, “This quality control process identified one batch of drug substance that did not meet quality standards at Emergent Biosolutions, a site not yet authorized to manufacture drug substance for our COVID-19 vaccine.”

“Last week we actually got a lot of Johnson & Johnson,” explained Dr. Marty Fenstersheib, the health officer leading Santa Clara County’s vaccination effort. “We had nearly 20,000 doses. Next week we’re only going to get 2,300 doses.”

Santa Clara is one county getting stung by the botched vaccine production on the other side of the country. Johnson & Johnson supplies will drop for at least a week, but that doesn’t mean vaccinations will stop.

“We do have the Moderna vaccine. We still have the Pfizer vaccine coming in,” said Fenstersheib. “So it’s not that we don’t have any vaccine.”

It does mean some counties will have to make some changes, not necessarily cancel appointments but prioritize people waiting for their second dose. And even at 15 million doses lost, the nationwide effort shouldn’t slow down all that much.

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“You know, we’ve done really well with Moderna and Pfizer,” said UC Berkeley epidemiologist Dr. John Swartzberg. “Those companies have delivered good products. And delivered them pretty much on schedule.”

So as for the larger schedule the state has been forecasting, vaccine abundance by May, there is no indication that one bad batch will change that.

“We’ve built a lot of resistance into the system,” Swartzberg said. “We really over-ordered if you will. Frankly, I’m delighted that we did that. So it’s given us the resiliency to make up for J&J’s fiasco.”

California is set to open up COVID vaccination eligibility to all residents over the age of 16 next week on April 15, but some parts of the Bay Area have already moved ahead with expanding eligibility.

Last week, Contra Costa County made the vaccination available to everyone who lives or works in the county over age 16 more than two weeks ahead of the state’s scheduled date.

Starting at midnight Thursday morning, Santa Clara County made hundreds of thousands of South Bay residents eligible to sign up to get vaccinated by allowing those age 16 and up to schedule vaccine appointments. However, the appointments still needed to fall on or after April 15.

Meanwhile, Alameda County on Thursday started administering COVID vaccines to people 16 and older in specific areas of Oakland, Hayward, San Leandro and San Lorenzo that have been hardest hit by the pandemic.

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The 12 zip codes that expanded the ages for vaccine eligibility in Alameda County are 94601, 94603, 94605, 94606, 94607, 94621, 94541, 94544, 94545, 94577, 94578 and 94580.