A new study has found that rapid antigen testing, which can be self-administered at home to monitor for COVID-19 infection, may not keep pace with the emerging forms of anxiety that cause SARS-CoV-2. different from the original stress.
The study, conducted by scientists at Harvard T.H. Chan School of Public Health and Beth Israel Deaconess Medical Center (BIDMC), found that some rapid antigen tests may not be as effective in detecting different COVID-19 variants.
While rapid antigen tests remain a useful tool in detecting COVID-19 infections, the study’s findings suggest that these tests will require “continuous evaluation” and updating taking into account variants of the virus.
The findings were published Thursday in the Journal of Clinical Microbiology.
Scientists say the main issue with the rapid tests is that they were developed with the original SARS-CoV-2 viral strain that emerged in late 2019. Since then, the virus has evolved several times and several viral forms of concern have emerged.
James Kirby, co-corresponding study author and BIDMC clinical director, said in a press release, “Unlike sensitive molecular tests, which detect multiple SARS-CoV-2 genes, rapid antigen tests detect a single viral protein. target.” “As the pandemic continues, however, some speculate that the performance of available antigen testing may differ between COVID forms of concern.”
Using live virus culture strains, the study’s authors assessed whether four commercially available rapid antigen tests were able to detect two COVID variants of concern — the highly infectious Delta and Omicron variants.
According to the study, the team observed a difference in the detection limit, which is the smallest amount of viral antigen detectable at 95 percent certainty, in the Binax, CareStart, GenBody and LumiraDx rapid tests.
The researchers found that all four tests were “more, if not more” sensitive to the Omicron variant than the original SARS-CoV-2 strain. Although three of the four tests showed low sensitivity to the delta variant, only the CareStart test showed “equal detection” of Omicron, Delta and the original virus.
Given the difference in the extent of the test’s detection, Kirby, who is also a professor at Harvard Medical School, says it could result in missing cases between the last two waves of the pandemic.
Kirby said in the release, “We expect that the observed loss in delta susceptibility could result in a 20 percent or greater loss of detection in potentially infectious individuals — yet, the most infectious individuals still should have been detected.” “
“However, our findings suggest that antigen testing performance for emerging variants needs to be re-evaluated to ensure that they still meet pandemic public health testing goals,” he said.
Given the unknown sensitivity of rapid tests with respect to COVID-19 variants, experts have previously advised Canadians to take two rapid tests to confirm whether they are infected or not.