At-home COVID-19 tests less effective after omicron emergence
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The performance of many COVID-19 home-testing kits worsened after the omicron variant emerged, according to a recent study.
“Self-testing for SARS-CoV-2 may potentially lower the threshold for testing and would allow individuals to obtain a result quickly and at their own convenience, which, in turn, could support the early detection of infectious people and reduce community transmission,” Ewoud Schuit, MSc, PhD, assistant professor at the University Medical Center Utrecht, and colleagues wrote. “Real-world evidence on the performance of unsupervised nasal and combined oropharyngeal and nasal self-sampling in the omicron variant period is needed to accurately inform end users and policymakers.”
To assess the performance of the rapid antigen tests with unsupervised nasal and combined oropharyngeal and nasal self-sampling during the omicron period, the researchers performed a prospective cross-sectional diagnostic test accuracy study. According to the study, the tests were performed on 6,497 people with COVID-19 symptoms aged 16 years and older at three public health service COVID-19 test sites in the Netherlands between Dec. 21, 2021, and Feb. 10, 2022. After being given a PCR test, study participants were given an at-home test within 3 hours to confirm results.
Overall, the study showed that the sensitivity of three rapid antigen tests — Flowflex, MPBio and Clinitest — declined as omicron transitioned from accounting for 29% of infections to more than 95% of infections. According to the study, sensitivity fell from 87% to 81% for Flowflex, from 83% to 76% for MPBio and from 80% to 67% for Clinitest, with only Clinitest reaching statistical significance. Additional oropharyngeal to nasal self-sampling — which was done only for MPBio and Clinitest — showed an improvement in the sensitivity from 70% to 83% for MPBio and 70% to 77% for Clinitest. The researchers noted that this improvement was most evident in people who visited the test site for reasons other than confirming a positive self-test result.
“We found that the performance of rapid antigen tests with nasal self-sampling declined during the period omicron emerged. We also showed that the performance of rapid antigen tests can be improved by adding oropharyngeal to nasal self-sampling,” the authors wrote. “Therefore, after proper evaluation, manufacturers of rapid antigen tests should consider extending their instructions for use to include combined oropharyngeal and nasal self-sampling.”
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