Those with antibodies appear to have immunity for at least a few months.
People who test positive for antibodies after being sick 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, known as serology tests, from five commercial labs and two healthcare data analytics companies between January and August 2020.
The researchers found that people with positive antibody tests had only about one-tenth the chance as those who had no antibodies to test positive for the virus 90 days after their first antibody test. After 90 days, a positive test likely represents a new infection rather than viral shedding of the original infection.
“The data from this study suggests that people who have a positive result on a commercial antibody test appear to have substantial immunity to SARS-CoV-2, which means they may have a lower risk of future infection,” said Dr. Lynne Penberthy, Associate. director of the National Cancer Institute’s surveillance research program, who led the study, said in a statement.
The results could help explain why reinfection appears to be relatively rare, and they could potentially guide future decisions about reopening work and school, as well as choices for vaccine distribution.
According to the researchers, additional research is needed to understand how long that protection lasts, who might receive less protection, and how differences between patients, such as underlying conditions, can affect protection against reinfection.
The study was published Wednesday in JAMA Internal Medicine.
Stephanie Ebbs of ABC News contributed to this report.
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