Los Angeles Should Reach Covid-19 Herd Immunity By Late June, Say Health Officials

Tom Tapp
·3 min read

On Wednesday, after months of not getting a three week window of projections on vaccine supply, Los Angeles County Public Health Director Barbara Ferrer said, based on numbers received from the federal government, that Los Angeles will reach 80% vaccine coverage in residents over 16 years old the next 12 weeks. That means by the end of June the county should have achieved the overall the 70-85% immunity — through vaccinations and infections — Dr. Anthony Fauci says is required for herd immunity to the virus.

“If L.A. County receives 500,000 doses a week,” said Ferrer on Wednesday, “80% vaccination of 16 and over can happen in just 12 more weeks.”

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According to U.S. Census data, 21.4% of Los Angeles County residents are under 18. Since all residents 16 and over will be eligible for vaccines on April 15, we’ll peg the percentage of those ineligible thereafter at 20%. In a county of 10 million, that equates to 2 million people. But many of those people have already been exposed to the virus.

Ferrer says that 30 to 40% of county residents have already been infected and so would have immunity. Fauci this week cited a study that asserted 45% of people in Los Angeles have Covid-19 antibodies. Assuming the majority of those people have not been vaccinated, one might then peg the number of immune L.A. residents under 16 with virus-exposed immunity at about 10% of the entire population.

Ferrer says that 80% of the remaining 16+ population should be vaccinated by late June — which comes out to 64% of overall residents. When one adds in the 10% of the under 16 population with virus-exposed immunity, it seems reasonable to say approximately 74% of all Los Angeles residents will have immunity by late June. That’s well within Fauci’s 70-85% requirement for herd immunity.

There are, of course, several variants of the virus swirling around L.A., but it is unclear how those will be impacted by immunity to the original strain.

Part of Ferrer’s presentation was a slide displaying the numbers behind her projections. To be clear, the graphic is based on an average of 576,000 doses arriving each week until then.

“We got the most vaccines this week being administered than we ever heave before,” said Ferrer before noting that “we have capacity here. We’re never going to be a situation here where we get additional doses and we can’t immediately get them in people’s arms.”

The director said the county got more doses than ever this week, but has built out the infrastructure to deliver doses at 630,000 appointments a week.

She also displayed in that graphic showing the four week projections provided by the federal government that allowed her to make the forward-looking assessment about vaccination rates. It indicated 500,000 doses this week and the next two and then 600,000 and 700,000 thereafter.

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