SARS-CoV-2 infection: use and effectiveness of antigenic swab for the health surveillance of healthcare workers
Main Article Content
Keywords
Health surveillance, Biological risk, Negative predictive value, COVID-19
Abstract
Background: The gold standard to identify SARS-CoV-2 infections is the Reverse Transcriptase-Polymerase Chain Reaction (RT-PCR) on rhino-pharyngeal swabs, but faster and cheaper methods such as antigenic swabs have been developed. A retrospective observational study on antigenic swabs included in the extraordinary health surveillance protocol of a large Hospital in Turin was aimed to assess their performance validity. Methods: From 30 October 2020 to 4 May 2021, 4000 antigenic swabs were carried out in three groups of healthcare workers (HCWs), respectively (i) asymptomatic, (ii) cohabiting with a positive case, and (iii) not recently exposed to the virus.
Results: Overall sensitivity and specificity associated with a prevalence of 1.30% were 26.9%, 97.2%, respectively, the corresponding positive (PPV) and negative predictive value (NPV) being 11.29% and 99.02% [95% IC (99.00 - 99.04)] respectively; a prevalence of 0.29% was observed in the asymptomatic group, among whom sensitivity and specificity were 25.0% and 98.9%, respectively, the corresponding PPV and NPV being 6.25% and 99.78% [95% IC (99.76 - 99.81)], respectively; the cohabitant group showed a prevalence of 21.11%, sensitivity and specificity were 47.4%, 81.7%, respectively, giving rise to a PPV of 40.91% and NPV of 85.29% [95% IC (85.18 – 85.41)] respectively. The prevalence in the not exposed group was 0.77%, sensitivity and specificity were 29.2%, 97.4%, respectively, and PPV and NPV 8.05% and 99.44% [95% IC (99.42 - 99.46)] respectively. Conclusions: Antigenic swabs reduced costs and provided reliable diagnostic results. In the cohabitant group, the higher-prevalence groups showed poor test performances, likely because of the high prevalence of pre-symptomatic illness in this group. Owing to the relatively low NPV, a negative result would still require confirmation with a molecular test to be acceptable for a surveillance program that effectively reduces the virus’s intra-hospital spread.
References
2. Gorbalenya AE, Baker SC, Baric RS, et al. The species Severe acute respiratory syndrome-related coronavirus: classifying 2019-nCoV and naming it SARS-CoV-2. Nat Microbiol. 2020;5(4):536-544. doi:10.1038/s41564-020-0695-z
3. World Health Organization. COVID-19 Weekly Epidemiological Update 22. World Heal Organ. 2021;(December):1-3. https://www.who.int/docs/default-source/coronaviruse/situation-reports/weekly_epidemiological_update_22.pdf
4. World Health Organisation. WHO Director-General’s opening remarks at the media briefing on COVID-19 - 11 March 2020. WHO Dir Gen speeches. 2020;(March):4. https://www.who.int/dg/speeches/detail/who-director-general-s-opening-remarks-at-the-media-briefing-on-covid-19---11-march-2020
5. ECDC. Options for the use of rapid antigen tests for COVID-19 in the EU/EEA and the UK. 2020;(November). https://www.biochemia-medica.com/en/journal/29/2/10.11613/BM.2019.021001
6. CDC. Interim Guidance for Antigen Testing for SARS-CoV-2. Centers Dis Control Prev. Published online 2020:1-8. https://www.cdc.gov/coronavirus/2019-ncov/lab/resources/antigen-tests-guidelines.html
7. WHO. Antigen-detection in the diagnosis of SARS-CoV-2 infection using rapid immunoassays Interim guidance, 11 September 2020. World Heal Organ. 2020;(September):1-9. https://apps.who.int/iris/handle/10665/334253
8. Falzone L, Gattuso G, Tsatsakis A, et al. Current and innovative methods for the diagnosis of COVID‑19 infection (Review). Int J Mol Med. 2021;47(6):1-23. doi:10.3892/ijmm.2021.4933
9. The COVID-19 Task force of the Department of Infectious Diseases and the IT Service Istituto Superiore di Sanità. COVID-19 Integrated Surveillance Data in Italy.; 2021. https://www.epicentro.iss.it/en/coronavirus/sars-cov-2-dashboard
10. Prevention C for DC and. Interim Operational Considerations for Public Health Management of Healthcare Workers Exposed to or with Suspected or Confirmed COVID-19: non-US Healthcare Settings. 2020;2019:1-7. https://search.bvsalud.org/global-literature-on-novel-coronavirus-2019-ncov/resource/en/grc-739970
11. Balestro C, Battaglio S, Bert F, et al. SARS-CoV2 Protocollo operativo per la gestione dell’emergenza Coronavirus nell’ Azienda Ospedaliero- Universitaria Città della Salute e della Scienza di Torino. Published online 2020.
12. LumiraDx SARS-CoV-2 Ag Test. https://www.fda.gov/media/141304/download
13. Drain PK, Ampajwala M, Chappel C, et al. A Rapid, High-Sensitivity SARS-CoV-2 Nucleocapsid Immunoassay to Aid Diagnosis of Acute COVID-19 at the Point of Care: A Clinical Performance Study. Infect Dis Ther. Published online 2021. doi:10.1007/s40121-021-00413-x
14. Bianco G, Boattini M, Barbui AM, et al. Evaluation of an antigen-based test for hospital point-of-care diagnosis of SARS-CoV-2 infection. J Clin Virol. 2021;139(February):104838. doi:10.1016/j.jcv.2021.104838
15. CDC. Antigen Testing Algorithm. https://www.cdc.gov/coronavirus/2019-ncov/lab/resources/Antigen_Testing_Algorithm_2020-12-14_v03_NO_DRAFT_SPW_508.pdf
Article Sidebar
Article Details
How to Cite
This is an Open Access article distributed under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by-nc/4.0) which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
Reproductions with commercial intent will require written permission and payment of royalties.
This work is licensed under a CC BY-NC-SA 4.0 Creative Commons Attribution-NonCommercial ShareAlike 4.0 International License.
How to Cite
