The number of people who have been infected with COVID-19 in Los Angeles County is greater than testing for the virus shows, according to a new study.
Public health officials say that’s because many people who are asymptomatic never get tested and not everyone who tests positive with an at-home kit reports their positive case to the county.
Using results of antibody tests performed on a control group, researchers found that the number of adults infected with COVID in L.A. County was three times higher than what tests showed between May and June of last year.
Among children, the numbers were even more dramatic, suggesting five times more children were actually infected than testing confirmed.
“The researchers estimated that at the time of the study, which was back in late spring of 2021, 30% of L.A. County adults had been infected and 37% of children had been infected,” county Public Health Director Barbara Ferrer said of the results from the CalScope study.
In that same time period, the county was only reporting infections in 10% of adults and slightly under 10% of children, she said.
She said the stark differences were due to shortcomings in the testing system. She noted that many people who may have been infected with the virus never got tested because they never got sick or developed any symptoms. Access to testing was also limited at times, preventing people from getting their infections confirmed.
Ferrer also said the current widespread availability of at-home testing is also affecting the official case count, since people who test at home aren’t necessarily reporting their results to the county.
The study data “can serve as an indication of the large number of infections that go unreported in L.A. County,” Ferrer said. “This is important to understand because it gives us a sense of the true scope and impact of the pandemic.”
Her comments came as the county sees a steady increase in infection rates, fueled by the infectious BA.2 subvariant of the virus. Based on the most recent genetic testing on COVID case samples in the county, the subvariant is now believed to account for 67% of all infections locally. That’s up from 47% a week ago and from 32% the week before that.
The numbers mean BA.2 is now confirmed as the dominant strain of the virus circulating in the county.
Ferrer said the county is now averaging more than 1,000 new cases per day over the past week, compared to 878 from the week prior.
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