(HealthDay News) — During the period of omicron emergence, the performance of COVID-19 rapid antigen tests with nasal self-sampling declined, according to a study published online Sept. 14 in The BMJ.
Ewoud Schuit, PhD, from Utrecht University in the Netherlands, and colleagues conducted a diagnostic test accuracy study at three public health service COVID-19 test sites from Dec. 21, 2021, to Feb. 10, 2022. Participants had a swab sample taken for reverse transcription polymerase chain reaction and received a rapid antigen test to perform unsupervised using nasal self-sampling (during the emergence of omicron and when omicron accounted for >90 percent of infections) or with combined oropharyngeal and nasal self-sampling (when omicron accounted for >99 percent of infections; phases 1 and 2, respectively). Flowflex (phase 1 only), MPBio and Clinitest were evaluated.
The researchers found that the overall sensitivities with nasal self-sampling were 79.0, 69.9, and 70.2% for Flowflex, MPBio and Clinitest, respectively. Compared with those tested for other reasons, the sensitivities were substantially higher in confirmatory testers (93.6, 83.6, and 85.7% versus 52.4, 51.5, and 49.5%, respectively). When transitioning from omicron accounting for 29% of infections to >95 percent of infections, the sensitivities decreased from 87 to 80.9 percent, 80.0 to 73%, and 83.1 to 70.3% (statistically significant), respectively. With combined oropharyngeal and nasal self-sampling, sensitivities were 83 and 77.3% for MPBio and Clinitest, respectively; sensitivities were slightly higher in confirmatory testers (87.4 and 86.1%, respectively) and substantially higher in those testing for other reasons (69.3 and 59.9%, respectively).
“The performance of rapid antigen tests can be improved by adding oropharyngeal to nasal self-sampling,” the authors write.
