At-home COVID-19 antigen self-tests reliable, user acceptable, safe

Self-performed rapid antigen detection tests (RADTs) are feasible and acceptable among laypeople, with the tests yielding higher sensitivities in the presence of symptoms and most individuals expressing preference for the at-home tests over a professionally administered nasopharyngeal RADT, as reported in a study.

“In this study, we evaluated two types of self-RADTs for analysing anterior nasal swab samples. Among all symptomatic and asymptomatic participants, the self-RADT sensitivities were 65.7 percent (DNA Diagnostic) and 62.1 percent (Hangzhou), and their specificities were 100 percent for both, compared to polymerase chain reaction (PCR) testing,” according to the investigators.

The analysis included 827 participants (mean age 42 years, 50.5 percent female), of which 102 showed positive PCR test results. Almost 15 percent of the cohort (n=119) had a health professional background. [Int J Infect Dis 2022;doi:10.1016/j.ijid.2022.01.019]

When participants were stratified into symptomatic and asymptomatic groups, the sensitivities tended to be higher in the symptomatic group for both the DNA Diagnostic RADT (76.0 percent vs 40.0 percent) and the Hangzhou RADT (66.7 percent vs 43.8 percent).

Generally, two out of three participants preferred self-RADT over the PCR test. The self-RADT was favoured mainly because it did not require a trip to the test centre for testing. Additionally, the participants liked that self-RADT had shorter response time and was easy to perform.

On the other hand, participants who preferred the PCR test reasoned that the test provided the most valid result, and that throat sampling was more comfortable than nose sampling. Some even mentioned that they felt more comfortable with a healthcare worker performing the test.

Among the 355 participants interviewed about safety issues, 12 (3.4 percent) reported nose bleeding. There was one participant who had to interrupt the self-test due to nose bleeding, which however did not require medical help. No other safety problems were reported.

“Our findings support the findings from previous studies, which showed no significant difference in diagnostic performance between samples collected by healthcare workers and those collected by participants. The sensitivities of self-RADTs observed in other studies ranged 49–96 percent, and the specificities ranged 82–100 percent,” according to the investigators. “The lowest sensitivity (49 percent) was observed among individuals with low viral loads.” [J Clin Microbiol 2021;59:e00569-21; Lancet Infect Dis 2021;21:1233-1245]  

Nevertheless, the investigators acknowledged that the inaccurate nature of self-reporting was a major weakness of their study. A professional read-out of the lateral flow RADT device might have increased the sensitivities. Furthermore, the participants were not observed performing the self-sampling procedure.

“To which extent the participants followed the instructions is unknown and inaccurate performance of the self-sampling may have caused false negative results in this study. On the other hand, our study aimed to assess the effectiveness of self-tests, which entailed a real-life situation, including self-assessments of test results,” they pointed out.

Despite the limitation, the study indicates that self-RADTs are a reliable and safe complementary test to PCR analyses of professionally collected oropharyngeal swab samples, the investigators said. Aside from reducing the time delay between the test performance and an available result, self-RADTs are cheap and easy to up- and downscale to meet the actual testing needs.

“These observations support the relevance of implementing self-RADTs as a supplement to professionally administered RADTs and PCR tests. Nevertheless, sufficient information should be provided to minimize the sense of false security among the individuals tested falsely negative with the RADTs,” they added.