Antibody testing raises questions about accuracy of official COVID-19 figures

Antibody testing in Santa Clara County, Calif. has raised questions about the official figures related to COVID-19 infections, according to a report published in the journal Nature on April 17.

The results of this study raise questions about the accuracy of official figures and indicate that the coronavirus is less deadly than the global cases and death count estimates suggest.

Researchers analyzed blood samples from 3,300 individuals living in Santa Clara county in early April. The results showed that 1 in 66 individuals had been infected with SARS CoV-2 at some point, and that changes the estimates of how many individuals have been affected by the virus at any time.

“On the basis of that finding, the researchers estimate that between 48,00 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,” the article says of results posted on medRxiv on April 17.

This is one of the first of more than a dozen surveys in progress that that look for the prevalence of antibodies of the coronavirus, and many of these tests use commercial antibody kits that look for the antibodies in blood samples.

“A sero-survey gives you a snapshot in time of who is infected in your given population,” said Kanta Subbarao, a virologist at the Peter Doherty Institute for Infection and Immunity in Melbourne.

This could be important to know for people who experience mild symptoms or none at all. The antibody will show up for people who had been infected for at a least a week, even without symptoms.

The Santa Clara study’s results follow a release of the results from a study in Germany that showed one in seven individuals in a group of 500 had been infected, who lived in a village of more than 12,000. They estimated that the German town had an overall infection rate of 15 percent.

Sero-surveys might give a more accurate estimate of how many people could die from SARS-CoV-2, by reporting an accurate infection fatality rate, which could help to improve the models that guide public health responses.