Rapid COVID-19 antigen tests may not be stored

BOSTON – By now, many are only too familiar with rapid antigen tests for the diagnosis of COVID-19. Slightly less accurate than genetic tests administered by healthcare professionals, the ease of use of rapid antigen tests allows the general public to monitor themselves for COVID-19 infections at home and make timely decisions to help to stop the spread. The home tests, however, were developed and gained federal authorization for use with the original SARS-CoV-2 virus strain that emerged in late 2019. Since then, the virus has evolved countless times and several virus variants of concern emerged, including the highly infectious delta and omicron variants that swept the United States in the summer and winter respectively.

In a recent study, scientists from Harvard TH Chan School of Public Health and Beth Israel Deaconess Medical Center used live virus culture to assess how well four rapid antigen tests are able to detect these concerning COVID variants. The results suggest that while rapid antigen tests remain a useful tool for detecting COVID-19 infections, continued evaluation and updating are likely needed in the context of variants of concern. Their work is published in the Journal of Clinical Microbiology.

“Unlike sensitive molecular tests that detect multiple SARS-CoV-2 genes, rapid antigen tests target a single viral protein,” said co-corresponding author James Kirby, MD, director of the BIDMC Clinical Microbiology Laboratory. “As the pandemic continues, however, some are speculating that the performance of the available antigen test may vary among the COVID variants of concern.”

Using three cultured live virus strains, the team assessed differences in the limits of detection (LoD) – the smallest amount of viral antigen detectable at 95% certainty – of four rapid antigen tests available in trade; Binax, CareStart, GenBody and LumiraDx tests. The researchers found that all four tests were as sensitive to the Omicron variant, if not more so, than they were to the original SARS-CoV-2 viral strain, known as WA1. Three tests, however, showed less sensitivity to the Delta strain, with only the CareStart showing equal detection of all three strains.

“We expect that the observed loss of Delta sensitivity could have resulted in a loss of detection of 20% or more in potentially infectious individuals – nevertheless, the most infectious individuals should still have been detected,” said Kirby, also professor of pathology at Harvard. Medicine School. “However, our results suggest that antigen test performance needs to be reassessed for emerging variants to ensure that they still meet pandemic public health testing goals.”

Co-authors included first author Sydney Stanley and co-senior corresponding author Phyllis J. Kanki of Harvard TH Chan School of Public Health; Stefan Riedel, Sanjucta Dutta, Elisa Contreras, Cody J. Callahan, Annie Cheng and Ramy Arnaout of BIDMC; Donald J. Hamel and Ian D. Wolf of Harvard TH Chan School of Public Health.

The authors acknowledge that Ginkgo Bioworks provided the CareStart and GenBody SARS-CoV-2 antigen test kits and that Abbott and LumiraDx provided their respective SARS-CoV-2 antigen test kits used in this study. For a full list of disclosures, please see the full study published by Journal of Clinical Microbiology.


About Beth Israel Deaconess Medical Center

Beth Israel Deaconess Medical Center is a patient care, teaching, and research affiliate of Harvard Medical School and consistently ranks among the national leaders among independent hospitals funded by the National Institutes of Health. BIDMC is the official hospital of the Boston Red Sox. For more information, visit www.bidmc.org.

Beth Israel Deaconess Medical Center is part of Beth Israel Lahey Health, a health care system that brings together academic medical centers and teaching hospitals, community and specialty hospitals, more than 4,800 physicians and 36,000 employees in a common mission to expand access to quality care. and to advance the science and practice of medicine through groundbreaking research and education.

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