Association of COVID-19 positive antibody test with future risk of infection

Editor's Note

This study, funded by the National Cancer Institute, National Institutes of Health, Bethesda, Maryland, finds that individuals who are antibody positive for COVID-19 based on commercial assays, versus those who are antibody negative, are at decreased risk of future COVID-19 infection.

In this analysis of 3,257,478 patients with an index antibody test, 88.3% were antibody negative and 11.6% were antibody positive.

Over a 90-day follow-up, the ratio of positive nucleic acid amplification test (NAAT) results in antibody-positive patients versus antibody-negative patients was substantially lower—an approximately 10-fold decrease—suggesting a protective effect of antibodies.

The duration of protection (10-fold) is comparable to that observed in the efficacy reports of mRNA vaccines in large clinical trials, the researchers say.