Field evaluation of a rapid antigen test (Panbio™ COVID-19 Ag Rapid Test Device) for COVID-19 diagnosis in primary healthcare centres

Abstract

Objectives: To our knowledge no previous study has assessed the performance of a rapid antigen diagnostic immunoassay (RAD) conducted at the point of care (POC). We evaluated the Panbio™ COVID-19 Ag Rapid Test Device for diagnosis of coronavirus 2019 disease (COVID-19) in symptomatic patients (n = 412) attending primary healthcare centres.

Methods: RAD was performed immediately after sampling following the manufacturer's instructions (reading at 15 min). RT-PCRs were carried out within 24 h of specimen collection. Samples displaying discordant results were processed for culture in Vero E6 cells. Presence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in cell cultures was confirmed by RT-PCR.

Results: Out of 412 patients, 43 (10.4%) tested positive by RT-PCR and RAD, and 358 (86.9%) tested negative by both methods; discordant results (RT-PCR+/RAD-) were obtained in 11 patients (2.7%). Overall specificity and sensitivity of rapid antigen detection (RAD) was 100% (95%CI 98.7-100%) and 79.6% (95%CI 67.0-88.8%), respectively, taking RT-PCR as the reference. Overall RAD negative predictive value for an estimated prevalence of 5% and 10% was 99% (95%CI 97.4-99.6%) and 97.9% (95%CI 95.9-98.9), respectively. SARS-CoV-2 could not be cultured from specimens yielding RT-PCR+/RAD- results (n = 11).

Conclusion: The Panbio™ COVID-19 Ag Rapid Test Device performed well as a POC test for early diagnosis of COVID-19 in primary healthcare centres. More crucially, the data suggested that patients with RT-PCR-proven COVID-19 testing negative by RAD are unlikely to be infectious.

Keywords: COVID-19; Early diagnosis; Primary healthcare centre; Rapid antigen detection test (RAD); SARS-CoV-2.

Fig. 1

(A) Field performance of the Panbio™ COVID-19 Ag Rapid Test Device (RAD) according to time between symptoms onset and testing (T values in specimens testing either RAD + or RAD–. (C) Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) RNA loads in specimens testing either RAD + or RAD–. The AMPLIRUN® TOTAL SARS-CoV-2 Control (Vircell SA, Granada, Spain) was used as the reference material for SARS-CoV-2 RNA load quantification (in copies/mL, considering RT-PCR C_Ts for the N gene; the linear regression equation was: Y = –0.31 × X + 13.77; R² = 9.89). Median and p values are shown.