Real-life validation of the Panbio™ COVID-19 antigen rapid test (Abbott) in community-dwelling subjects with symptoms of potential SARS-CoV-2 infection

Abstract

Background: RT-qPCR is the reference test for identification of active SARS-CoV-2 infection, but is associated with diagnostic delay. Antigen detection assays can generate results within 20 min and outside of laboratory settings. Yet, their diagnostic test performance in real life settings has not been determined.

Methods: The diagnostic value of the Panbio™ COVID-19 Ag Rapid Test (Abbott), was determined in comparison to RT-qPCR (Seegene Allplex) in community-dwelling mildly symptomatic subjects in a medium (Utrecht, the Netherlands) and high endemic area (Aruba), using two concurrently obtained nasopharyngeal swabs.Findings: 1367 and 208 subjects were enrolled in Utrecht and Aruba, respectively. SARS-CoV-2 prevalence, based on RT-qPCR, was 10.2% (n = 139) and 30.3% (n = 63) in Utrecht and Aruba respectively. Specificity of the Panbio™ COVID-19 Ag Rapid Test was 100% (95%CI: 99.7-100%) in both settings. Test sensitivity was 72.6% (95%CI: 64.5-79.9%) in the Netherlands and 81.0% (95% CI: 69.0-89.8%) in Aruba. Probability of false negative results was associated with RT-qPCR Ct-values, but not with duration of symptoms. Restricting RT-qPCR test positivity to Ct-values <32 yielded test sensitivities of 95.2% (95%CI: 89.3-98.5%) in Utrecht and 98.0% (95%CI: 89.2-99.95%) in Aruba.

Interpretation: In community-dwelling subjects with mild respiratory symptoms the Panbio™ COVID-19 Ag Rapid Test had 100% specificity, and a sensitivity above 95% for nasopharyngeal samples when using Ct-values <32 cycles as cut-off for RT-qPCR test positivity. Considering short turnaround times, user friendliness, low costs and opportunities for decentralized testing, this test can improve our efforts to control transmission of SARS-CoV-2.

Fig. 1

PCR and LFA results of all subjects. All PCR results for the three targets are shown by Ct-value on the y-axis (left side: positive PCR results per target; right side: negative PCR results), grouped based on the LFA result on x-axis.

Fig. 2

Association between Ct-value and LFA test result. All dots reflect positive PCR results, shown on the x-axis at the observed Ct-value of the E-gene. gray dots reflect positive LFA samples, white dots negative LFA samples. The red line reflects the probability of a positive LFA based per Ct-value, the red dotted line denotes the point where 50% of LFAs are expected to become positive.

Fig. 3

Ct-value of positive subjects grouped by duration of symptoms. The dots represent individuals with positive PCR results shown on the y-axis based on the lowest observed Ct-value in any of the three targets. The dots are groups based on the duration of symptoms. gray dots represent positive LFA results, white dots negative LFA results. Horizontal lines of the boxes are median and IQR; whiskers extend to the minimum and maximum.