Study examines the diagnostic performance of rapid antigen tests during Omicron and Delta waves in South Africa

4 September 2023

Study examines the diagnostic performance of rapid antigen tests during Omicron and Delta waves in South Africa

Two field studies evaluating the performance of rapid antigen tests in identifying SARS-CoV-2 Delta and Omicron strains have shown robust outcomes providing data on the accuracy of detection, which hopefully will continue for future coronavirus variants.

The study by Samsunder et al. published in the Journal of Clinical Virology evaluated the performance of two widely used rapid antigen tests to identify Omicron sub-lineages BA.4 and BA.5, on samples collected from 540 study participants from KwaZulu-Natal, South Africa. Results showed a sensitivity of >90% in the detection of infections with Omicron BA.4/BA.5 sub-lineage. 

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.  

Additionally a study published recently in the Diagnostic and Prognostic Research journal by Samsunder et al. evaluated four rapid antigen tests for identification of SARS-CoV-2 infections during the Delta wave in South Africa.  

The overall sensitivity for all four tests on 1033 samples ranged between 60 and 72% with excellent specificity (> 98%). Sensitivity increased to > 80% in all tests in samples with cycle number value < 20. 

They concluded that the performance of the evaluated rapid antigen tests targeting SARS-CoV-2 nucleocapsid protein were not affected by the emergence of new SARS-CoV-2 variants. Rapid antigen tests continue to play an important role in the control of Covid-19 pandemic


For further reading see:

Samsunder N et al. Field evaluations of four SARS-CoV-2 rapid antigen tests during SARS-CoV-2 Delta variant wave in South Africa. Diagnostic and Prognostic Research (BMC). 2023 July;7(1):14.  Samsunder N et al. Performance of rapid antigen tests in identifying Omicron BA.4 and BA.5 infections in South Africa. Journal of Clinical Virology. 2023 August; 165:105498.

Figure: Sensitivity of the AllTest SARS-CoV-2 Rapid Ag and the Standard Q COVID-19 Ag tests