ImplemeNting SARS-CoV-2 Rapid antigen testing in the Emergency wArd of a Swiss univErsity hospital: the INCREASE study

Abstract

Background: While facing a second wave in SARS-CoV-2 pandemic, in November 2020 the Swiss Federal Office of Public Health (FOPH) authorized the use of rapid antigen tests (RATs) in addition to the gold-standard reverse transcription-polymerase chain reaction (RT-PCR). Methods: We implemented the use of RAT in the emergency ward of our university hospital for rapid patients' triaging and compared performances of four different antigen tests. All results were compared to SARS-CoV-2 specific RT-PCR (reference standard). Findings: Triaging patients using RAT in association with RT-PCR allowed us to isolate promptly positive patients and to save resources, in a context of rapid RT-PCR reagents shortage. Among 532 patients with valid results, overall sensitivities were 48.3% for One Step Exdia and 41.2% for Standard Q, PanbioTM and BD Veritor. All four antigen tests exhibited specificity above 99%. Sensitivity increased up to 74.6%, 66.2%, 66.2% and 64.8% for One Step Exdia, Standard Q, Panbio, and BD Veritor respectively, when considering viral loads above 105copies/ml, up to 100%, 97.8%, 96.6% and 95.6% for viral loads above 106 copies/ml and 100% (for all tests) when considering viral loads above 107 copies/ml. Sensitivity was significantly higher for patients presenting with symptoms onset within 4 days (74.3%, 69.2%, 69.2% and 64%, respectively) versus patients with evolution of symptoms for more than 4 days (36.8%, 21.1%, 21.1% and 23.7%, respectively). Sensitivities of all RAT assays were of only 33% among hospitalized patients without COVID-19 symptoms. Interpretation: RAT might represent a useful epidemiological resource in selected clinical settings as a complementary tool to the molecular tests for rapid patients triaging, but the lower sensitivity compared to RT-PCR, especially in late presenters and subjects without COVID-19 symptoms, must be taken into account in order to correctly use RAT for triaging.

Multi-centre post-implementation evaluation of SARS-CoV-2 antigen-based point of care tests used for asymptomatic screening of continuing care healthcare workers

“…Both tests were initially authorised by the FDA and Health Canada for the diagnosis of COVID-19 within the first five (Veritor) to seven (Panbio) days of COVID-19 symptom onset [16]. Our findings are consistent with the literature, demonstrating the PPVs for the Veritor in asymptomatic individuals ranging from 24.9-50.1% (with disease prevalence of 0.5-1.5%) [24] and that of the Panbio to be 28.0-54.0%, using prevalence estimates of 0.5-1.5% [24-26]. Thus, the Panbio would be preferred over the Veritor for asymptomatic screening of COVID-19.…”

Sensitivity of rapid antigen testing and RT-PCR performed on nasopharyngeal swabs versus saliva samples in COVID-19 hospitalized patients: results of a prospective comparative trial (RESTART)

“…RAT yielded high diagnostic performances only for patients with high VL (≥10 6 copies/ml) (supplementary material, S4_Figure 3). The much lower diagnostic performances of RAT in saliva might be explained by the lower VL in saliva as compared to NP swabs or eventually the presence of mucosal secretory immunoglobulins targeting SARS-CoV-2 antigens and thus competing with RAT for the same target (14,23).…”

“…Patients were predominantly males (n=45, 77%) with a median age of years-old (IQR 61-77). Most of them still had symptoms upon sampling (n=49, 84%) with a median duration of symptoms of 11 days (IQR, [5][6][7][8][9][10][11][12][13][14][15][16][17][18][19]. Common symptoms on presentation were dyspnea (n=27, 46%), cough (n=19, 33%) and fever (n=10, 17%).…”

“…Little is known on the utility and diagnostic performances of the above-mentioned strategies in moderately to severely ill hospitalized patients. Current literature shows discordant results, depending on the clinical setting studied, the sampling method or even the use or not of a viral transport medium (VTM) (2)(3)(4)(5)(6)(9)(10)(11)(12)(13)(14)(15)(16)(17).…”

The dark side of SARS-CoV-2 rapid antigen testing: screening asymptomatic patients

“…In this study, performed with Standard Q ® COVID-19 Rapid Antigen Test (SD Biosensor/Roche) on nasopharyngeal samples, sensitivity was 75.3% and specificity 100%, with a COVID-19 prevalence of 32.8%. After the implementation of RAT at the Emergency Department of the Lausanne University Hospital (CHUV) for quick triaging of patients with or without COVID-19 symptoms 9 , we applied a combined RAT and RT-PCR nasopharyngeal screening to asymptomatic patients admitted in the Emergency Department of a 250-bed community hospital (EHC) in Morges, Switzerland.…”