S.F. testing at nearly double rate of L.A.
Health officials and medical experts say that testing is key to understanding the coronavirus pandemic sweeping the world. But a new analysis from the Bay Area News Group found widespread differences in testing rates across California — with San Francisco and Santa Clara counties testing at nearly double the rate of Los Angeles County.
And that could have major implications when it comes to public understanding of where and how the deadly disease is spreading — and perhaps more crucially, when it is safe to stop sheltering at home.
San Francisco has the highest per capita testing rate of large counties in the state, according to the news group’s analysis, with about 714 of every 100,000 residents being tested. San Diego’s per capita testing rate — around 656 tests for every 100,000 people — is similarly high. Santa Clara, which became the state’s first major center for the virus, is testing about 679 of every 100,000 residents.
But Los Angeles, the mostalarming hot spot in the Golden State, has tested only about 374 of every 100,000 residents, a testing rate below the state average of
roughly 443 tests per 100,000 people.
Why the wildly different testing rates? Private labs stepping up to reinforce limited efforts by public health departments may be one reason, experts say, and demographic differences may also be playing a role.
But it’s hard to know for sure, and the counties don’t all report data in the same way, so pinning down precise testing rates is difficult. And there are some holes — about 10 of California’s 58 counties so far have failed to provide testing data at all.
San Francisco is clearly getting outside help. George Rutherford, professor of epidemiology at UC San Francisco, said the Chan Zuckerberg Biohub — a medical science research center from Dr. Priscilla Chan and Facebook founder Mark Zuckerberg, her husband — repurposed itself into a certified clinical lab. That’s provided a huge boost in San Francisco’s daily testing capacity, adding around 3,000 tests a day and pushing toward the 4,000-a-day figure he’d like to see.
“It’s a huge jump,” Rutherford said. “That solution fell out of the sky.”
His colleague Ralph Gonzales, associate dean for clinical innovation and chief innovation officer for UCSF Health, said one reason testing is lower in Los Angeles could be that the county has a higher proportion of residents in the 18-and-younger age group, a cohort that has been much less affected by the coronavirus and may not be seeking out testing as often. That could mean Los Angeles County’s testing rate of older age groups might be closer in line with other counties with older populations who are getting tested more frequently.
But, Gonzales said, “I wasn’t expecting to see L.A. so low.”
Gonzales also pointed out that Los Angeles County — with a population more than 10 times that of San Francisco — would need to conduct a huge number of tests to approach the same testing rate. In a theory echoed by others, he suggested that limitations on testing materials, like swabs, could be translating into the lower testing rates.
The Los Angeles County Department of Public Health did not immediately respond to a request for comment regarding testing rates.
Public health officials across the country have been frustrated by the federal government’s rollout
of coronavirus testing, blaming a shortage of testing kits for allowing the deadly virus to spread unchecked and with little warning across the nation. With the crisis hitting the hardest now on the East Coast, New York is testing at almost three times the rate of San Francisco — and more than five times the rate of L.A.
Los Angeles Mayor Eric Garcetti recently said that the city was boosting testing capacity and that any resident of the county with symptoms of the virus can get tested. So the county’s testing rate could rise as more people seek tests in the coming days.
Robert Siegel, a microbiology and immunology professor at Stanford University, said L.A. County is so large that the data may be obscuring some nuances. Perhaps, he said, per capita testing rates are higher near testing sites such as UCLA but lower in outlying places where testing isn’t readily accessible.
“It may be so big, that it may look like multiple counties,” Siegel said.
To the south, San Diego officials and medical professionals worked to ramp up testing ahead of an expected surge of COVID-19 patients, said UC San Diego infectious disease specialist David Pride.
“We’ve got a large amount of testing capacity, but demand is not nearly what we thought it was going to be,” Pride said of the San Diego area.
But in a hot spot such as Los Angeles, he said, he’s “doubtful they could test everybody who wants to be tested.”
In the biotech-rich, five-county Bay Area, where testing rates range from around 400 tests per 100,000 residents in Alameda
County to about 761 tests per 100,000 residents in San Mateo, testing has evolved quickly — from a Hayward fire station offering free testing to Stanford deploying one of the first blood tests to check for antibodies.
Elsewhere, Plumas County in the northeast has the highest testing rate — at more than 1,200 tests per 100,000 people — followed by Humboldt County. On the low end, Glenn, Madera and Tehama counties are testing fewer than 220 residents per 100,000 people.
One option, Pride said, is for the state to do a better job of moving available tests to areas where there is a need for more testing — similar to efforts now to share desperately needed medical equipment and protective gear.
“Folks just need to develop the relationships and send the tests,” he said.
Regardless of the differences, medical experts say the data suggests California needs far more testing, period.
“What I was struck by is that there are not enough tests overall,” said Warner Greene at the Gladstone Institutes of Virology and Immunology. “We seem to have been slow to test.”
In places such as South Korea and Singapore, where testing and contact tracing have been extensive, officials have a better sense of where the virus is, where people with antibodies are, even if they never showed symptoms, and when it’s safe to allow some people to return to work.
Without that information, “we’re flying blind,” Greene said. “We need to have eyes on this infection.”