More than four percent of Californians may have developed antibodies against the novel coronavirus, preliminary results of a new study suggest.
Researchers from the University of Southern California developed a coronavirus antibody test, which can determine if someone has been infected and if their body has produced immune cells that can protect them from being reinfected.
They teamed up with officials from the Los Angeles County Department of Public Health to test residents aged 18 and older.
Results from the first round of testing showed that between 2.8 percent and 5.6 percent – with an average of 4.1 percent – have antibodies against the virus.
This means that between 221,000 and 442,000 adults in the county have had the virus – 28 to 55 times higher than the roughly 8,000 confirmed cases of the virus.
It comes on the heels of a study from Stanford University that also found four percent of the state’s population has likely been infected.
The University of Southern California and the Los Angeles County Department of Public Health began coronavirus antibody testing earlier this month (above)
Between 2.8 percent and 5.6 percent – with an average of 4.1 percent – of adults in Los Angeles County have antibodies against the virus. Pictured: Antibody testing in Niteroi, Brazi, April 17
These results show the actual number of confirmed cases in Los Angeles County is likely between 221,000 and 442,000 – 28 to 55 times higher than the 8,000 reported. Pictured: A resident is transported from St Mark Village in Palm Harbor, Florida, April 20
Researchers say the preliminary results suggest coronavirus infections are far more widespread, with a much lower fatality, rate in Los Angeles County than it was believed.
‘We haven’t known the true extent of COVID-19 infections in our community because we have only tested people with symptoms, and the availability of tests has been limited,’ lead investigator Dr Neeraj Sood, a professor of public policy at USC, said in a press release.
‘The estimates also suggest that we might have to recalibrate disease prediction models and rethink public health strategies.’
Health experts say antibody tests could help scientists understand how widespread the virus is and how long patients remain immune after they recover.
This is important because it could allow immune people to leave their homes and return to work to ‘jump start the economy’ as well as help healthcare workers determine if they are immune.
‘These results indicate that many persons may have been unknowingly infected and at risk of transmitting the virus to others,’ said Dr Barbara Ferrer, director of the LA County Department of Public Health.
‘These findings underscore the importance of expanded…testing to diagnose those with infection so they can be isolated and quarantined, while also maintaining the broad social distancing interventions.’
For the study, scientists conducted drive-through antibody testing on April 10 and 11 at six different sites.
Participants were recruited by the market services firm LRW Group using a large proprietary database.
Researchers used a rapid antibody test manufactured by Premier Biotech, which was then validated by a laboratory at Stanford University.
The authors say their results have not yet been peer reviewed.
Over the next few months, they plan to test new groups of participants every few weeks to determine the pandemic’s trajectory in Los Angeles County.
The had previously advised against using antibody tests to diagnose coronavirus because it takes times for antibodies to develop.
But, on earlier this month, the FDA issued an Emergency Use Authorization for the first antibody tests for Cellex Inc, a medical device company based in North Carolina.
This indicates that the agency believes the benefits outweigh any risks.
‘Based on the totality of scientific evidence available to FDA, it is reasonable to believe that your product may be effective in diagnosing COVID-19,’ FDA chief scientist Denise Hinton wrote in a letter to James Li, the CEO of Cellex.
‘The known and potential benefits of your product when used for diagnosing COVID-19, outweigh the known and potential risks of your product.’
The tests used presently involve a nasal or throat swab, and try to identify the virus’s genetic material to see if someone is currently infected.
This new test requires blood to be collected either through a vein or from a finger prick, and can only be analyzed in a certified laboratory. It looks to see if someone has ever been exposed and is now immune.
According to the FDA, the antibodies against the novel coronavirus are ‘generally detectable in blood several days after initial infection.’
But the agency warned in its letter that ‘levels over the course of infection are not well characterized.