Those with antibodies appear to have immunity for at least a few months.
People who test positive for antibodies after falling ill with the virus that causes COVID-19 may have protection against reinfection for at least a few months, according to a new study.
Researchers at the National Institutes of Health analyzed 3 million antibody test results, also known as serology tests, from five commercial laboratories and two health data analysis companies between January and August 2020.
The researchers found that people with positive antibody tests were only about a tenth as likely to test positive for the virus than those who had no antibodies 90 days after the initial antibody test. After 90 days, a positive test probably represents a new infection, rather than viral spread from the original infection.
“The data from this study suggests that people with a positive result in a commercial antibody test appear to have substantial immunity to SARS-CoV-2, which means that they may have a lower risk of future infection,” Dr. Lynne Penberthy, associate O director of the National Cancer Institute’s surveillance research program, which led the study, said in a statement.
The results can help explain why reinfection appears to be relatively rare and can guide future decisions about reopening work and school, as well as vaccine distribution choices.
According to the researchers, additional research is needed to understand how long this protection lasts, who may have less protection and how differences between patients, such as underlying conditions, can affect protection against reinfection.
The study was published on Wednesday in JAMA Internal Medicine.
Stephanie Ebbs of ABC News contributed to this report.
What to know about the coronavirus:
Tune in ABC at 1 pm ET and ABC News Live at 4 pm ET every day of the week for special coverage of the coronavirus novel with the full ABC News team, including the latest news, context and analysis.