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. 2023 Aug:165:105498.
doi: 10.1016/j.jcv.2023.105498. Epub 2023 Jun 2.

Performance of rapid antigen tests in identifying Omicron BA.4 and BA.5 infections in South Africa

Natasha Samsunder  1 , Gila Lustig  1 , Margaretha de Vos  2 , Sinaye Ngcapu  3 , Jennifer Giandhari  4 , Derek Tshiabuila  4 , Emmanuel James San  4 , Lara Lewis  1 , Ayesha Bm Kharsany  3 , Cherie Cawood  5 , Tulio de Oliveira  6 , Quarraisha Abdool Karim  7 , Salim Abdool Karim  7 , Camille Escadafal  2 , Kogieleum Naidoo  8 , Aida Sivro  9
Affiliations

Performance of rapid antigen tests in identifying Omicron BA.4 and BA.5 infections in South Africa

Natasha Samsunder et al. J Clin Virol. 2023 Aug.

Abstract

Background: Concerns around accuracy and performance of rapid antigen tests continue to be raised with the emergence of new SARS-CoV-2 variants.

Objective: To evaluate the performance of two widely used SARS-CoV-2 rapid antigen tests during BA.4/BA.5 SARS-CoV-2 wave in South Africa (May - June 2022).

Study design: A prospective field evaluation compared the SARS-CoV-2 Antigen Rapid test from Hangzhou AllTest Biotech (nasal swab) and the Standard Q COVID-19 Rapid Antigen test from SD Biosensor (nasopharyngeal swab) to the Abbott RealTime SARS-CoV-2 assay (nasopharyngeal swab) on samples collected from 540 study participants.

Results: Overall 28.52% (154/540) were SARS-CoV-2 RT-PCR positive with median cycle number value of 12.30 (IQR 9.30-19.40). Out of the 99 successfully sequenced SARS-CoV-2 positive samples, 18 were classified as BA.4 and 56 were classified as BA.5. The overall sensitivities of the AllTest SARS-CoV-2 Ag test and Standard Q COVID-19 Ag test were 73.38% (95% CI 65.89-79.73) and 74.03% (95% CI 66.58-80.31) and their specificities were 97.41% (95% CI 95.30-98.59) and 99.22% (95% CI 97.74-99.74) respectively. Sensitivity was >90% when the cycle number value was <20. The sensitivity of both rapid tests was >90% in samples infected with Omicron sub-lineage BA.4 and BA.5.

Conclusion: Accuracy of tested rapid antigen tests that target the nucleocapsid SARS-CoV-2 protein, were not adversely affected by BA.4 and BA.5 Omicron sub-variants.

Keywords: Antigen; BA.4, BA.5; COVID-19; Omicron; SARS-CoV-2; Sensitivity; Specificity.

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Conflict of interest statement

Declaration of Competing Interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: Antigen rapid diagnostic tests were provided by FIND, the global alliance for diagnostics, and FIND was involved in the study design development. CE and MdV are employees of FIND. The rest of the authors declare no conflict of interests.

Figures

Fig 1
Fig. 1
Sensitivity of the AllTest SARS-CoV-2 Rapid Ag and the Standard Q COVID-19 Ag tests across different categories (CN value, presence and duration of symptoms, vaccination and SARS-CoV-2 lineage. The error bars represent 95% Confidence interval.
See this image and copyright information in PMC

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