A study suggests that substantially more people have been infected by the coronavirus than what Los Angeles County’s confirmed case count shows, backing previous findings from preliminary serology findings reported last month.
The study tested 865 people for coronavirus antibodies during the second week of April, when roughly 8,430 cases of the virus had been confirmed in L.A. County. The findings suggest that the prevalence of antibodies among residents was 4.65%, an estimate that implies about 367,000 adults had been infected by the virus at the time. The preliminary findings reported last month estimated that 4.1% of county residents had contracted the virus.
The ongoing study from USC and L.A. County’s Public Health Department was published Monday in the Journal of the American Medical Assn.
The study indicates that the county has a long way to go before herd immunity is established. Neeraj Sood, the study’s lead author, also said the findings suggest that contact tracing methods to track and limit the spread of the virus could be challenging. Contact tracing — the process of identifying individuals who may have come into contact with an infected patient — is one of the state’s requirements before counties can expand their reopenings.
Samples were taken from a random group of people in a 15-mile radius of eligible testing sites.Two tests were inconclusive because of faulty kits. Of those whose tests were used, 60% were women, 55% were ages 35-54, 58% were white and 43% had yearly household incomes greater than $100,000.
More than 38,000 L.A. County residents have tested positive for the virus — a number that accounts for the bulk of the state’s total of more than 80,000 infections. But officials have long warned the public that confirmed cases do not represent the true totality of the virus’ spread.
As testing capacity has increased, so has the number of confirmed cases. But to date, only about 350,000 of the county’s 10 million residents have been checked. Of those, 9% have tested positive.
The county continues to ease certain restrictions to restore the economy, while stressing the need for residents to maintain social-distancing practices. Most retail stores and restaurants allow curbside pickup, trails and parks have reopened and active recreation is allowed at the beaches. Face masks are still required, while gatherings are not permitted in the county.
Although several counties have been given permission for dine-in service and in-store shopping — and more counties are making cases for further reopening — the grip the coronavirus has on L.A. County is holding fast. The county’s case count and death toll have not seen a decline like in some rural areas. Officials continue to grapple with how to reopen the economy without triggering a resurgence of the outbreak.
“We’re many parts, and every part of the state of California is unique and distinctive,” Gov. Gavin Newsom said Monday when asked about the state’s patchwork of modifications. The governor noted that urban areas like L.A. County and the Bay Area may not be ready to move as quickly as other communities.
L.A. County remains the center of the pandemic in California, with more than 1,800 deaths. Despite the toll, there have been positive signs.
As L.A. County found itself in a coronavirus crisis in March, it became clear the highly infectious disease was surging out of control in the county, with every one person testing positive for the virus infecting an average of 3½ other people.
Last week, L.A. County officials released data showing remarkable progress: The infection rate has fallen. Instead of every patient infecting an average of more than three other people, every infected person in L.A. County now infects just one other person.
Among L.A. County public health experts, this number is called “R,” which stands for the Effective Transmission Number of the disease. This number can change when the public takes steps to change behaviors, such as adhering to a stay-at-home order.
The fact that the disease was spreading from one infected person to more than three others represented “a high rate of spread, much faster than what is seen, for example, with seasonal influenza,” Dr. Christina Ghaly, director of health services for L.A. County, said Thursday.
Officials believe the drop is tied to stay-at-home orders imposed in late March.
“This represents tremendous progress, and we should all be very proud. It is also what allows us to start easing health officer orders and the restrictions that we’ve all been living with for the past several weeks. Safer at Home bought us time,” Ghaly said.
“It allowed our healthcare system to become more prepared. It allowed time for testing to be ramped up. It allowed time to prepare to do more contact tracing efforts, and it showed the power of what we can all do to protect ourselves and one another.”