Diagnostic performance of rapid antigen testing for SARS-CoV-2: the COVid-19 AntiGen (COVAG) extension study

Christoph Wertenauer; Alexander Dressel; Eberhard Wieland; Hans-Jörg Wertenauer; Helmine Braitmaier; Anna Straub; Stefan Helfert; Nicolas Lützner; Winfried März

doi:10.3389/fmed.2024.1352633

Diagnostic performance of rapid antigen testing for SARS-CoV-2: the COVid-19 AntiGen (COVAG) extension study

Front Med (Lausanne). 2024 Apr 16:11:1352633. doi: 10.3389/fmed.2024.1352633. eCollection 2024.

Authors

Christoph Wertenauer^{1

2

3}, Alexander Dressel⁴, Eberhard Wieland⁵, Hans-Jörg Wertenauer², Helmine Braitmaier⁵, Anna Straub⁵, Stefan Helfert⁶, Nicolas Lützner⁵, Winfried März^{1

7

8}

Affiliations

¹ Medical Clinic V, Medical Faculty Mannheim, University of Heidelberg, Mannheim, Germany.
² Hausärzte am Schillerplatz, Stuttgart, Germany.
³ SYNLAB Holding Deutschland GmbH, Augsburg, Germany.
⁴ Dr. Dressel Consulting, Mannheim, Germany.
⁵ SYNLAB Medical Care Center Leinfelden-Echterdingen GmbH, Leinfelden-Echterdingen, Germany.
⁶ SYNLAB MVZ Humangenetik Mannheim GmbH, Mannheim, Germany.
⁷ SYNLAB Academy, SYNLAB Holding Deutschland GmbH, Mannheim, Germany.
⁸ Clinical Institute of Medical and Chemical Laboratory Diagnostics, Medical University of Graz, Graz, Austria.

Abstract

Background: This study is the extension of the COVAG study. We compared two RATs, the Panbio COVID-19 Ag Rapid Test (Abbott) and the SD Biosensor Q SARS-CoV-2 Rapid Antigen Test (Roche), against RT-PCR on the foil of new variants.

Methods: We included 888 all-comers at a diagnostic center between October 20, 2021, and March 18, 2022. RT-PCR-positive samples with a Ct value ≤32 were examined for SARS-CoV-2 variants.

Findings: The sensitivity of the Abbott-RAT and Roche-RAT were 65 and 67%, respectively. For both RATs, lower Ct values were significantly correlated with higher sensitivity. For samples with Ct values ≤25, the sensitivities of the Roche-RAT and of the Abbott-RAT were 96 and 95%, for Ct values 25-30 both were 19%, and for Ct values ≥30 they were 6 and 2%, respectively. The RATs had substantially higher sensitivities in symptomatic than asymptomatic participants (76, 77%, vs. 29, 31%, for Abbott-RAT, Roche-RAT, respectively) and in participants referred to testing by their primary care physician (84, 85%) compared to participants who sought testing due to referral by the health department (55, 58%) or a warning by the Corona-Warn-App (49, 49%). In persons with self-reported previous COVID-19 sensitivities were markedly lower than in patients without previous COVID-19: 27% vs. 75% for Roche-RAT and 27% vs. 73% for Abbott-RAT. We did not find significant correlation between vaccination status and sensitivity. The Omicron variant was detected with a sensitivity of 94 and 92%, the delta variant with a sensitivity of 80 and 80% for Abbott-RAT and Roche-RAT, respectively. This difference is attributable to the lower Ct values of the Omicron samples compared to the Delta samples. When adjusted for the Ct value, a multivariate logistic regression did not show a significant difference between Omicron and Delta. In terms of sensitivity, we found no significant difference between the wild-type and the Omicron and Delta variants, but a significantly lower sensitivity to the alpha variant compared to the other variants.The specificities were > 99% overall.

Keywords: COVID-19; SARS-CoV-2; antigen test; delta; diagnostic; omicron; rapid antigen detection test; variants.

Grants and funding

The author(s) declare financial support was received for the research, authorship, and/or publication of this article. The costs of the study were defrayed by SYNLAB Holding Deutschland GmbH. The management had no role in writing of the report or the decision to submit for publication. There was no financial support to SYNLAB Holding Deutschland GmbH from the manufacturers of the assays used in this evaluation and there has been no other financial support for this work that could have influenced its outcome.