Impact of Omicron variant sublineage BA.2.75 on the OnSite COVID-19 Ag Rapid Test: the applicability of rapid antigen test with universal transport media

Infect Dis (Lond). 2024 Feb;56(2):138-144. doi: 10.1080/23744235.2023.2280025. Epub 2023 Dec 18.

Abstract

Background: Rapid antigen testing (RAT) is one of the most powerful tools for SARS-CoV-2 detection. The OnSite COVID-19 Ag Rapid Test is an antigen-based, point-of-care test approved by the WHO for Emergency Use Listing. The Nucleocapsid (N) gene mutations found in the emerging Omicron sublineages lead to the question of RAT performance.

Objective: To ensure the diagnostic performance of the study RAT during rapidly mutated Omicron variants.

Results: We independently evaluated the performance of this assay in 1098 archived samples collected in Thailand during October 2022-February 2023, which were 798 and 300 COVID-19 real-time RT-PCR positive and negative, respectively. The assay performed with 100% sensitivity and 100% specificity using a cycle threshold (Ct) of <20 for the RT-PCR. The sensitivity decreased to 88% when using Ct <30. Most of the SARS-CoV-2 found were Omicron BA.2 (99%), harboring six known N mutations (P13L, E31del, S33del, R203K, G204R and S413R). Eight samples containing hybrid variants (XBB.1*, XBB.2 and XBJ) were detected by the study RAT. This RAT detects all Omicron sublineages known to be circulating in Thailand.

Conclusions: These results confirmed the good performance of the study RAT for detecting Omicron variants and its appropriateness for individual diagnosis and for genomic surveillance.

Keywords: Omicron variant; SARS-CoV-2; diagnostic performance; rapid antigen test.

MeSH terms

  • COVID-19* / diagnosis
  • Humans
  • Mutation
  • Real-Time Polymerase Chain Reaction
  • SARS-CoV-2 / genetics

Supplementary concepts

  • SARS-CoV-2 variants