Researchers looked at more than 3 million people who had an antibody test for SARS-CoV-2. SARS-CoV-2 is the virus that causes COVID-19.
Image: A cell from a patient (purple) infected with SARS-CoV-2 (blue) Image Credit: NIAID
They found that about 11% of people had SARS-CoV-2 antibodies. More than 88% had a negative test. And less than 1% of tests were inconclusive.
The scientists looked at who came down with COVID-19 after the test. They analyzed up to 30 days, 31–60 days, 61–90 days, and more than 90 days after.
About 3% to 4% of people with negative antibody tests got COVID-19 in each time period. But those who had antibodies were less likely to have COVID-19 as time went on. Only 0.3% of the people with antibodies had a positive COVID-19 test more than 90 days after. Those without antibodies were 10 times more likely to get the disease.
The findings suggest that people who have a positive result from an antibody test may be at lower risk for future infection with SARS-CoV-2.
NIH’s Dr. Lynn Penberthy, who led the research team, explains that more questions still need to be answered. “We are nevertheless encouraged by this early finding,” she says.
