The lack of supply comes as vaccine eligibility in California expands to everyone aged 16 and over starting Thursday.
But while the decline in the county-controlled supply is concerning, there are still expected to be about a half-million available doses in the county, thanks to other non-county or city providers who receive direct allocations from the state and federal governments.
"Taken together, we estimate that well over 500,000 doses of vaccine will be allocated to vaccination sites across the county next week," said Dr. Paul Simon, chief science officer for the county Department of Public Health.
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The county's allocation of vaccine for next week is expected to total 323,470, Simon said. That's a roughly 74,000-dose drop from this week, with the reduction due to a major drop in availability of the Johnson & Johnson single-dose vaccine. The county received about 97,000 doses of that vaccine this week, but will only receive about 20,000 next week.
Simon said the county's allocations of Pfizer and Moderna vaccines will both increase, but not enough to make up for the Johnson & Johnson dropoff.
Only about 785,000 doses of the Johnson & Johnson vaccine are expected nationwide compared to 5 million this week. There was a problem with a plant in Baltimore that had issues manufacturing the vaccine.
"This is a national phenomenon. We felt the effects here clearly next week. We really sort of live week to week with what we know about the allocations," Simon said. "We have not really gotten a longer time horizon."
As vaccination numbers continue to rise across Southern California, there remains a disparity in who is getting a shot. In L.A. County, more than 40% of Asian residents have gotten at least one dose. It's more than 37% for white residents, but for the Black and Hispanic population, it's down at 22.7%.
Meanwhile, churches are becoming part of the strategy to vaccinate L.A. County communities. St Patrick's Church in South L.A. is reaching out to the area, which has been one of the hardest hit during the pandemic with nearly 70,000 positive cases and more than 1,000 deaths.
The church is a congregation of about 3,000 families. It has been part of the community since the 1920s and church officials say it is very important for those families to have access to vaccinations.
"This has been weeks in the making. We are very, very excited to have people here," said Sandra Olmedo of St. Patrick's Church. "We thought it was really important to bring the vaccines to the community instead of sending the community out to the vaccines."
Friday's vaccination clinic at St. Patrick's Church and a personal protective equipment giveaway in downtown L.A. were held to help Black and brown communities hit hard by the pandemic.
With eligibility set to open up to everyone 16 and older next week, there is still not enough doses.
"We are quite concerned with this opening up of eligibility," Simon said. "Virtually now everybody 16 and older - that those with less resources, less ability to navigate these online appointment systems, will have more difficulty getting appointments and that could have the unfortunate consequence of worsening these disparities."
City News Service contributed to this report.