Widespread antibody testing in a Californian county has revealed a much higher prevalence of coronavirus infection than official figures suggested.
The findings also indicate that the virus is less deadly than current estimates of global case and death counts suggest.
But some scientists have raised concerns about the accuracy of kits used in such studies because most have not been rigorously assessed to confirm they are reliable.
An analysis of the blood of some 3,300 people living in Santa Clara county in early April found that one in every 66 people had been infected with SARS-CoV-2.
On the basis of that finding, the researchers estimate that between 48,000 and 82,000 of the county’s roughly 2 million inhabitants were infected with the virus at that time — numbers that contrast sharply with the official case count of some 1,000 people reported in early April, according to the analysis posted today on medRxiv. The work has not yet been peer reviewed.