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. 2021 Feb 2;8(3):ofab059.
doi: 10.1093/ofid/ofab059. eCollection 2021 Mar.

Nasopharyngeal Panbio COVID-19 Antigen Performed at Point-of-Care Has a High Sensitivity in Symptomatic and Asymptomatic Patients With Higher Risk for Transmission and Older Age

Mar Masiá  1   2 , Marta Fernández-González  1 , Manuel Sánchez  3 , Mar Carvajal  1 , José Alberto García  1 , Nieves Gonzalo-Jiménez  4 , Victoria Ortiz de la Tabla  5 , Vanesa Agulló  1 , Inmaculada Candela  6 , Jorge Guijarro  7 , José Antonio Gutiérrez  8 , Carlos de Gregorio  3 , Félix Gutiérrez  1   2
Affiliations

Nasopharyngeal Panbio COVID-19 Antigen Performed at Point-of-Care Has a High Sensitivity in Symptomatic and Asymptomatic Patients With Higher Risk for Transmission and Older Age

Mar Masiá et al. Open Forum Infect Dis. .

Abstract

Background: Performance of point-of-care tests in different clinical scenarios and on different samples remains undetermined. We comprehensively evaluated the performance of the nasopharyngeal Panbio COVID-19 Ag Rapid Test Device.

Methods: This is a prospective study that includes consecutive patients attending 3 primary care centers (PCCs) and an emergency department. The antigen test was performed at point-of-care in nasopharyngeal and nasal swabs and in saliva. Positive percent agreement (PPA) and negative percent agreement (NPA) were calculated with the reverse-transcription polymerase chain reaction (RT-PCR) assay as reference standard.

Results: Of 913 patients included, 296 (32.3%) were asymptomatic and 690 (75.6%) came from the PCC. Nasopharyngeal swabs were collected from 913 patients, nasal swabs were collected from 659 patients, and saliva was collected from 611 patients. The RT-PCR was positive in 196 (21.5%) nasopharyngeal samples (NPS). Overall, PPA (95% CI) in NPS was 60.5% (53.3-67.4), and it was lower in nasal swabs (44.7%) and saliva (23.1%). Test performance in NPS was largely dependent on the cycle threshold (Ct) in RT-PCR, with PPA of 94% for Ct ≤25 and 80% for Ct <30. In symptomatic patients, the PPA was 95% for Ct ≤25, 85% for Ct <30, and 89% for the symptom triad of fever, cough, and malaise. Performance was also dependent on age, with a PPA of 100% in symptomatic patients >50 years with Ct <25. In asymptomatic patients, the PPA was 86% for Ct <25. In all cases, NPA was 100%.

Conclusions: The nasopharyngeal Panbio COVID-19 Ag test performed at point-of-care has a good sensitivity in symptomatic patients with Ct <30 and older age. The test was useful to identify asymptomatic patients with lower Ct values.

Keywords: COVID-19; Panbio; SARS-CoV-2; antigen; point-of-care.

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Figures

Figure 1.
Figure 1.
Performance of Panbio COVID-19 Ag Rapid Test Device by type of sample.
Figure 2.
Figure 2.
Performance of nasopharyngeal Panbio COVID-19 Ag Rapid Test Device in different scenarios. (A) Performance according to cycle threshold (Ct) values. (B) Performance according to age.
Figure 3.
Figure 3.
Performance of nasopharyngeal Panbio COVID-19 Ag Rapid Test Device after stratification for different factors. (A) Performance stratified by the presence of symptoms, age, and cycle threshold (Ct) values. (B) Performance stratified by symptom duration and age.
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