Evaluation of the Abbott Panbio™ COVID-19 antigen detection rapid diagnostic test among healthcare workers in elderly care

Abstract

Background: Coronavirus disease 2019 (COVID-19) has been especially dangerous for elderly people. To reduce the risk of transmission from healthcare workers to elderly people, it is of utmost importance to detect possible severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) positive healthcare workers as early as possible. We aimed to determine whether the Abbott Panbio™ COVID-19 antigen detection rapid diagnostic test (Ag-RDT) could be used as an alternative to reverse transcription-quantitative polymerase chain reaction (RT-qPCR). The second aim was to compare the cycle threshold (Ct) in RT-qPCR with the results of the Ag-RDT.

Methods: A prospective diagnostic evaluation of the Abbott Panbio™ COVID-19 Ag-RDT among healthcare workers across three elderly care facilities as well as home-based elderly care workers who met clinical criteria for COVID-19 during the second wave of the COVID-19 pandemic. Per healthcare worker, the first nasopharyngeal swab was obtained to perform the Ag-RDT and the second swab for RT-qPCR. A Ct-value of < 40 was interpreted as positive, ≥ 40 as negative.

Results: A total of 683 healthcare workers with COVID-19 symptoms were sampled for detection of SARS-CoV-2 by both Ag-RDT and RT-qPCR. Sixty-three healthcare workers (9.2%) tested positive for SARS-CoV-2 by RT-qPCR. The overall sensitivity of Ag-RDT was 81.0% sensitivity (95%CI: 69.6-88.8%) and 100% specificity (95%CI: 99.4-100%). Using a cut-off Ct-value of 32, the sensitivity increased to 92.7% (95% CI: 82.7-97.1%). Negative Ag-RDT results were moderately associated with higher Ct-values (r = 0.62) compared to positive Ag-RDT results.

Conclusion: The Panbio™ COVID-19 Ag-RDT can be used to quickly detect positive SARS-CoV-2 healthcare workers. Negative Ag-RDT should be confirmed by RT-qPCR. In case of severe understaffing and with careful consideration, fully vaccinated healthcare workers with Ag-RDT negative results could work with a mask pending PCR results.

Fig 1. RT-qPCR cycle thresholds (Ct) in specimen of healthcare workers with COVID-19 symptoms testing either negative or positive by Panbio^™ COVID-19 antigen detection rapid test.

The figure shows the frequency of the median cycle thresholds (Ct) in RT-qPCR in specimen from healthcare workers with COVID-19 symptoms testing either negative or positive by Panbio^™ COVID-19 antigen detection rapid test. PCR, RT-qPCR; LFA, lateral flow assay.

Fig 2. Negative predictive values of Panbio^™ COVID-19 antigen detection rapid test for different prevalence of SARS-CoV-2.

The figure shows negative predictive values and their 95% confidence intervals of the Panbio^™ COVID-19 antigen detection rapid test for different prevalence of SARS-CoV-2 determined against RT-qPCR among healthcare workers working in elderly care facilities as well as in home-based elderly care who met clinical criteria for COVID-19.