News and Commentary

Los Angeles Just Extended Lockdown. But Do Californians Have Herd Immunity?
LOS ANGELES, CA - JANUARY 7: Fresh snow blankets the mountains behind the downtown skyline after a series of storms that hammered northern California delivered much needed precipitation to the Greater Los Angeles Area January 7, 2008 in Los Angeles, California. With the threat of mandatory water rationing still in effect because of prolonged drought, the rain is a small step toward relief. Forecasters had predicted flash floods and mudslides near large areas that were denuded by wildfires of historic proportions in October, and some mandatory evacuations were declared, but little damage was reported.
(Photo by David McNew/Getty Images)

Los Angeles officials announced Friday that they would be extending the lockdown of non-essential businesses, and keeping the county’s stay-at-home order until at least May 15, prolonging the restlessness of millions of residents who were hoping to see relaxed guidelines later this month.

At a press conference, Dr. Barbara Ferrer, the head of the Los Angeles County Department of Health, said that while the measures have been effective, continuing to implement them was still necessary because “we still have a ways to go,” reports Los Angeles Magazine.

But the personal grief and the economic anxiety associated with the lockdown has prompted curiosity about recent news reports, which suggest that Californians may have been stricken with the coronavirus early, and have already begun to develop a form of herd immunity.

The report, first conducted by ABC-7, notes that researchers at Stanford University have started conducting an antibody test study to determine how many Bay Area residents may have contracted coronavirus undetected.

The report also cites Victor Davis Hanson, a historian at the Hoover Institution at Stanford University, as suggesting that travelers from China may have been bringing the coronavirus to California since last year, before it was first detected in the United States.

While the results are not expected to be released until several weeks from now, so far, there is no strong evidence that Californians have been covertly contracting coronavirus before others in the country.

For starters, Stanford Medicine recently told Slate that the coronavirus 2019 theory isn’t supported by it’s current research. But many people have also pointed to California’s strong, early flu season as evidence that the coronavirus may have been spreading covertly.

However, the California Department of Health has previously indicated that the viruses spreading around in late 2019 were actually multiple strains of the flu, reports The Sacramento Bee.

“We’re seeing a bit of everything right now,” said Erin Murray, a California state epidemiologist. “We are seeing predominately influenza B/Victoria virus this year in California at the moment, and this is also being seen nationally. But we are also seeing influenza H1N1 and H3N2 viruses here in California, so we have a real mix.”

As for the coronavirus, in a recent small study that is currently under peer-review, a team of researchers analyzed the virus genomes of 29 California-based patients who tested positive for the virus, and determined that the patients were infected from at least eight different lineages, including lineages from China, Europe, and Washington state.

Virus genomes were sampled from 29 patients diagnosed with COVID-19 infection from Feb 3rd through Mar 15th. Phylogenetic analyses revealed at least 8 different SARS-CoV-2 lineages, suggesting multiple independent introductions of the virus into the state…

These findings suggest that cryptic transmission of SARS-CoV-2 in Northern California to date is characterized by multiple transmission chains that originate via distinct introductions from international and interstate travel, rather than widespread community transmission of a single predominant lineage.

That said, the study includes the following note:

We note that this does not exclude the possibility of cryptic transmission of multiple lineages in California, as the current level of sampling is not dense enough to estimate confidently the dates of the seeding events, nor the subsequent periods of cryptic transmission before a lineage was identified.

A separate study of Washington determined that the state’s coronavirus outbreak likely came from a single introductory event at some point in January or February, “strongly suggesting cryptic spread of COVID-19 during the months of January and February 2020, before active community surveillance was implemented.”

We demonstrate that SARS-CoV-2 was circulating in Washington State for 4-6 weeks before the first community-acquired case was detected on 28 February, 2020. Refining the time and geographic origin of the introduction into Washington State will require a combination of earlier samples and samples from other geographic locations, including from elsewhere in the United States and from China.