Microbiology Spectrum (Aug 2022)

Analytical Sensitivity of Eight Different SARS-CoV-2 Antigen-Detecting Rapid Tests for Omicron-BA.1 Variant

  • Meriem Bekliz,
  • Kenneth Adea,
  • Olha Puhach,
  • Francisco Perez-Rodriguez,
  • Stéfane Marques Melancia,
  • Stephanie Baggio,
  • Anna-Rita Corvaglia,
  • Frederique Jacquerioz,
  • Catia Alvarez,
  • Manel Essaidi-Laziosi,
  • Camille Escadafal,
  • Laurent Kaiser,
  • Isabella Eckerle

DOI
https://doi.org/10.1128/spectrum.00853-22
Journal volume & issue
Vol. 10, no. 4

Abstract

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ABSTRACT The emergence of each novel SARS-CoV-2 variant of concern (VOC) requires investigation of its potential impact on the performance of diagnostic tests in use, including antigen-detecting rapid diagnostic tests (Ag-RDTs). Although anecdotal reports have been circulating that the newly emerged Omicron-BA.1 variant is in principle detectable by Ag-RDTs, few data on sensitivity are available. We have performed (i) analytical sensitivity testing with cultured virus in eight Ag-RDTs and (ii) retrospective testing in duplicates with clinical samples from vaccinated individuals with Omicron-BA.1 (n = 59) or Delta (n = 54) breakthrough infection on seven Ag-RDTs. Overall, in our analytical study we have found heterogenicity between Ag-RDTs for detecting Omicron-BA.1. When using cultured virus, we observed a trend toward lower endpoint sensitivity for Omicron-BA.1 detection than for earlier circulating SARS-CoV-2 and the other VOCs. In our retrospective study, the detection of Delta and Omicron-BA.1 was assessed in a comparable set of stored clinical samples using seven Ag-RDTs. Four hundred ninety-seven of all 826 tests (60.17%) performed on Omicron-BA.1 samples were positive, compared to 489/756 (64.68%) for Delta samples. In the analytical study, the sensitivity for both Omicron-BA.1 and Delta between the Ag-RDTs was variable. All seven Ag-RDTs showed comparable sensitivities to detect Omicron-BA.1 and Delta in the retrospective study. IMPORTANCE Sensitivity for detecting Omicron-BA.1 shows high heterogenicity between Ag-RDTs, necessitating a careful consideration when using these tests to guide infection prevention measures. Analytical and retrospective testing is a proxy and timely solution to generate rapid performance data, but it is not a replacement for clinical evaluations, which are urgently needed. Biological and technical reasons for detection failure by some Ag-RDTs need to be further investigated.

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