Those with antibodies appear to have immunity for at least a few months.
People who have tested positive for antibodies after getting 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 results of antibody tests, also known as serology tests, from five commercial laboratories and two health care data analysis companies in January-August 2020.
The researchers found that people with positive antibody tests were only about one-tenth as likely as those without antibodies to test positive for the virus 90 days after the initial antibody test. After 90 days, a positive test is a new infection rather than a viral elimination from the initial infection.
“Data from this study suggest that people who test positive for a commercial antibody test appear to have substantial immunity to SARS-CoV-2, which means they may be at lower risk for future infection.” The director of the National Cancer Institute’s surveillance research program, which led the study, said in a statement.
The results could explain why reinfection seems relatively rare and could guide future decisions about reopening work and school, as well as vaccine distribution choices.
According to the researchers, further research is needed to understand how long that protection lasts, who may have less protection and how differences between patients, such as baseline conditions, could affect protection against reinfection.
The study was published Wednesday in JAMA Internal Medicine.
Stephanie Ebbs of ABC News contributed to the report.
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