NIH study finds that people with antibodies to SARS-CoV-2 may be at low risk of future infection


Press release

Wednesday, February 24, 2021

People who have had evidence of a previous infection with SARS-CoV-2, the virus that causes COVID-19, appear to be well protected against reinfection with the virus, at least for a few months, according to a recently published study from the Institute. National Cancer Institute (NCI). This finding may explain why reinfection appears to be relatively rare and could have important implications for public health, including decisions about returning to physical workplaces, school attendance, prioritizing vaccine distribution, and others. activities.

For the study, researchers at NCI, part of the National Institutes of Health, collaborated with two healthcare data analytics companies (HealthVerity and Aetion, Inc.) and five commercial laboratories. The findings were published on February 24 in JAMA Internal Medicine.

“While cancer research and cancer care remain the primary focus of NCI’s work, we were eager to bring our serological science expertise to help address the global COVID-19 pandemic, at the request of Congress,” he said. NCI Director Norman E. “Ned” Sharpless, MD, who was one of the study’s co-authors. “We hope that these results, in combination with those of other studies, will inform future public health efforts and help set policy.”

“The 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 have a lower risk of future infection,” said Lynne Penberthy. , MD MPH, associate director of the NCI Surveillance Research Program, who led the study. “More research is needed to understand how long this protection lasts, who may have limited protection, and how patient characteristics, such as comorbid conditions, can affect protection. However, we are encouraged by this initial finding. ”

Antibody tests, also known as serological tests, detect serum antibodies, which are proteins of the immune system made in response to a foreign substance or a specific infectious agent, such as SARS-CoV-2.

This study was launched in an effort to better understand whether, and to what extent, detectable antibodies to SARS-CoV-2 protect people from reinfection by the virus. Working with HealthVerity and Aetion, NCI collected and analyzed patient information collected from multiple sources, including five commercial laboratories (including Quest Diagnostics and Labcorp), electronic medical records, and private insurers. This was done in a way that protects the privacy of an individual’s medical information and complies with the relevant patient privacy laws.

Researchers finally obtained antibody test results for more than 3 million people who underwent a SARS-CoV-2 antibody test between January 1 and August 23, 2020. This represented more than 50% of commercial SARS-CoV-2 antibody tests. performed in the United States during that time. Almost 12% of these tests were positive for antibodies; most of the remaining tests were negative and less than 1% were inconclusive.

Approximately 11% of seropositive individuals and 9.5% of seronegative individuals subsequently received a nucleic acid amplification test (NAAT), sometimes referred to as a PCR test, for SARS-CoV-2. The research team looked at what fraction of individuals in each group subsequently tested positive for NAAT, which may indicate a new infection. The study team reviewed the NAAT results at various intervals: 0-30 days, 31-60 days, 61-90 days, and> 90 days because some people who have recovered from a SARS-CoV-2 infection are still able to clear viral material (RNA) for up to three months (although they will probably not remain infectious throughout that period).

The team found that, during each interval, between 3% and 4% of the seronegative individuals had a positive NAAT test. But among those who had originally been HIV-positive, the NAAT test positivity rate decreased over time. When the researchers looked at the test results 90 or more days after the initial antibody test (when any coronavirus detected by NAAT is likely to reflect a new infection rather than a continued spread of the virus from the original infection), only about 0.3% of those who had been HIV-positive had a positive NAAT result, about one-tenth the rate in those who had been HIV-negative.

Although these results support the idea that having antibodies to SARS-CoV-2 is associated with protection from future infections, the authors point to important limitations in this study. In particular, the findings come from a scientific interpretation of real-world data, which are subject to biases that can be better controlled in a clinical trial. For example, it is not known why people who tested positive for antibodies underwent a PCR test. Furthermore, the duration of protection is unknown; Studies with a longer follow-up time are needed to determine whether protection decreases over time.

To continue to comprehensively address this important research question, NCI is supporting clinical studies that monitor infection rates in large populations of people whose antibody status is known. These are known as “seroprotection” studies. The NCI also sponsors ongoing studies that use real-world data to assess the long-term effect of antibody positivity on subsequent infection rates.

This research is part of a $ 306 million effort that the NCI has undertaken at the request of Congress to develop, validate, improve and implement serological tests and associated technologies applicable to COVID-19. Through this assignment, NCI is working with the Department of Health and Human Services; the National Institute of Allergy and Infectious Diseases, another part of the NIH; and other government agencies to apply their experience and advanced research capabilities to respond to this pandemic, including efforts to rigorously characterize the performance of serological tests.

About the National Cancer Institute (NCI): NCI leads the efforts of the National Cancer Program and NIH to dramatically reduce the prevalence of cancer and improve the lives of cancer patients and their families, through research on the prevention and biology of cancer, the development of new interventions and training and mentoring of new researchers. For more information about cancer, visit the NCI website at cancer.gov or call the NCI contact center, Cancer Information Service, at 1-800-4-CANCER (1-800-422- 6237).

About the National Institutes of Health (NIH):NIH, the nation’s medical research agency, includes 27 institutes and centers and is a component of the U.S. Department of Health and Human Services.The NIH is the primary federal agency conducting and supporting basic, clinical, and medical research. translational, and is researching the causes, treatments, and cures for common and rare diseases. For more information on NIH and its programs, visit www.nih.gov.

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