Low sensitivity of rapid tests detecting anti-CoV-2 IgG and IgM in health care workers’ serum for COVID-19 screening

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Francesca Larese Filon
Antonio Purpuri
Davide Camata
Massimo Bovenzi
Francesca Rui
Federico Ronchese
Paola De Michieli
Alessandro Marcello
Monica Poggianella
Marco Confalonieri
Francesco Salton
Paola Confalonieri
Maurizio Ruscio
Anna Belgrano
Ludovica Segat
Pierlanfranco D'Agaro
Corrado Negro


COVID-19, epidemiology, health care workers, diagnostic tests, IgG antibody


Background: the sensitivity and specificity of a rapid antibody test were investigated for the screening of healthcare workers. Methods: the serum of 389 health care workers exposed to COVID-19 patients or with symptoms, were analysed. All workers underwent monthly the screening for SARS-CoV-2 with detection of viral RNA in nasopharyngeal swabs by RT-PCR. IgG antibody detection in serum was performed by Chemiluminescence Immunoassay (CLIA) and by the Rapid test (KHB diagnostic kit for SARS CoV-2 IgM/IgG antibody after a median of 7.6 weeks (25°-75° percentiles 6.6-11.5). Results: the rapid test resulted positive in 31/132 (23.5%), 16/135 (11.8%) and 0/122 cases in COVID-19 positive individuals, in those with only SARS-CoV-2 IgG antibodies and in those negative for both tests, respectively. Sensitivity was 17.6% (CI95% 13.2-22.7) and 23.5% (CI95% 16.5-31.6), and specificity was 100% (CI95% 97-100) and 100% (CI95% 97-100) considering Rapid test vs CLIA IgG or Rapid test vs SARS-CoV-2 positive RNA detection, respectively. Conclusion: the KHB Rapid test is not suitable for the screening of workers with previous COVID-19 infection.


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1. Long QX, Liu BZ, H.I. Deng, G.C.Wu, et al. Antibody responses to SARS-CoV-2 in patients with COVID-19. Nat Med. 2020; 26, 845–848. Doi 10.1038/s41591-020-0897-1.
2. Yongchen Z, Shen H, Wang X, et al. Different longitudinal patterns of nucleic acid and serology testing results based on disease severity of COVID-19 patients. Emerg Microbes Infect.2020; 833–836; https:// doi.org/10.1080/22221751.2020.1756699.
3. World Health Organization, 2020. Laboratory testing for coronavirus disease 2019 (COVID-19) in suspected hu-man cases: interim guidance, 2 March 2020. World Health Organization. Available at: https://apps.who.int/iris/bitstream/handle/10665/331329/WHO-COVID-19-laboratory-2020.4- eng.pdf?sequence=1&isAllowed=y (last access 15 January 2021).
4. Petherick A. Developing antibody tests for SARS-CoV-2. Lancet 2020; 395, 1101–1102.
5. Bélec L, Péré H, Mboumba Bouassa RS, et al. Potential pitfalls of routine SARS-CoV-2 serology for mass screen-ing. J Med Virol 2020, 10.1002/jmv.26034.
6. Lau EHY, Tsang OTY, Hui DSC, et al. Neutralizing antibody titres in SARS-CoV-2 infections. Nat Commun. 2021; 12, 63; doi: 10.1038/s41467-020-20247-4
7. Meschi S, Colavita F, Bordi L, et al. Performance evaluation of Abbott ARCHITECT SARS-CoV-2 IgG immunoas-say in comparison with indirect immunofluorescence and virus microneutralization test. J Clin Virol.2020; 129,104539; https://doi.org/10.1016/j.jcv.2020.104539.
8. Nicol T, Lefeuvre C, Serri O, Pivert A, et al. Assessment of SARSCoV- 2 serological tests for the diagnosis of COVID-19 through the evaluation of three immunoassays: two automated immunoassays (Euroimmun and Ab-bott) and one rapid lateral flow immunoassay (NG Biotech). J Clin Virol. 2020; 129, 104511 https://doi.org/10.1016/j.jcv.2020.104511.
9. Charpentier C, Ichou H, Damond F, et al. Performance evaluation of two SARS-CoV-2 IgG/IgM rapid tests (Covid-Presto and NG-Test) and one IgG automated immunoassay (Abbott). J Clin Virol 2020; 132,104618; doi: 10.1016/j.jcv.2020.104618.
10. Ducancelle A, Lunel-Fabiani F, Le Guillou-Guillemette H. Assessment of SARSCoV- 2 serological tests for the diagnosis of COVID-19 through the evaluation of three immunoassays: two automated immunoassays (Euro-immun and Abbott) and one rapid lateral flow immunoassay (NG Biotech). J Clin Virol 2020; 129, 104511, https://doi.org/10.1016/j.jcv.2020.104511.
11. Hoffman T, Nissen K, Krambrich J, et al. Evaluation of a COVID-19 IgM and IgG rapid test; an efficient tool for assessment of past exposure to SARS-CoV-2. Infect Ecol Epidemiol 2020; 14,10,1754538; doi: 10.1080/20008686.2020.1754538. eCollection 2020.
12. Dellière S, Salmona M, Minier M, et al. CORE (COvid REsearch) group Evaluation of the COVID-19 IgG/IgM Rapid Test from Orient Gene Biotech J Clin Microbiol 2020; 23, 58(8):e01233-20; doi: 10.1128/JCM.01233-20.
13. Péré H, Bouassa RM, Tonen-Wolyec S, et al. Analytical performances of five SARS-CoV-2 whole-blood finger-stick IgG-IgM combined antibody rapid tests. J Virol Methods 2021; 18, 114067.
14. Pistelli L, Sitzia C, Carrara M, et al. Anti-SARS CoV2 antibody testing in healthcare workers: comparison be-tween rapid-cassette tests, ELISA and CLIA methods. J Biol Regul Homeost Agents 2020; 34,2359-2363.
15. Ong DSY, de Man DJ, Lindeboom FA, Koeleman JGM. Comparison of diagnostic accuracies of rapid serological tests and ELISA to molecular diagnostics in patients with suspected coronavirus disease 2019 presenting to the hospital. Clin Microbiol Infect 2020; 26, 1094.e7-1094.e10. doi: 10.1016/j.cmi.2020.05.028.
16. Deeks JJ, Dinnes J, Takwoingi Y, et al. Cochrane COVID-19 Diagnostic Test Accuracy Group. Antibody tests for identification of current and past infection with SARS-CoV-2. Cochrane Database Syst Rev 2020;25, CD013652; doi: 10.1002/14651858.CD013652.
17. Milani GP, Dioni L, Favero C, et al. UNICORN Consortium. Serological follow-up of SARS-CoV-2 in asympto-matic subjects Sci Rep. 2020; 18,10(1):20048. doi: 10.1038/s41598-020-77125-8
18. Piapan L, De Michieli P, Ronchese F, et al. COVID-19 outbreak in healthcare workers in hospitals in Trieste, North-east Italy. J Hosp Infect. 2020; 106(3), 626-628. Doi: 10.1016/j.jhin.2020.08.012.

19. Calagnan E, Gobbato M, Burba I, et al. COVID-19 infections in the Friuli Venezia Giulia Region (Northern Italy): a population-based retrospective analysis. Epidemiol Prev. 2020; 44(5-6 Suppl 2),323-329. doi: 10.19191/EP20.5-6.S2.133.
20. CDC-Centre Diseases Control, Interim U.S. Guidance for Risk Assessment and Work Restrictions for Healthcare Personnel with Potential Exposure to SARS-CoV-2, https://www.cdc.gov/coronavirus/2019-ncov/hcp/guidance-risk-assesment-hcp.html (accessed March 2020).
21. Tré-Hardy M, Wilmet A, Beukinga I, et al. Validation of a chemiluminescent assay for specific SARS-CoV-2 anti-body. Clin Chem Lab Med 2020; 28,1357-1364; doi: 10.1515/cclm-2020-0594.
22. World Health Organization (WHO). Coronavirus disease (COVID-19) technical guidance: Laboratory testing for 2019-nCoV in humans. 2020. Available at: https://www.who.int/emergencies/diseases/novel-coronavirus-2019/technical-guidance/laboratory-guidance. (Accessed April 15, 2020).
23. Youden WJ. Index for rating diagnostic tests. Cancer 1950; 3, 32–35.
24. Ayouba A, Thaurignac G, Morquin D, et al. Multiplex detection and dynamics of IgG antibodies to SARS-CoV2 and the highly pathogenic human coronaviruses SARS-CoV and MERS-CoV J Clin Virol 2020; 129, 104521. doi: 10.1016/j.jcv.2020.104521
25. Woloshin S, Patel N, Kesselheim AS. False Negative Tests for SARS-CoV-2 Infection - Challenges and Implica-tions.
N Engl J Med. 2020 Aug 6;383(6):e38. doi: 10.1056/NEJMp201589
26. Sethuraman N, Jeremiah SS, Ryo A. Interpreting diagnostic tests for SARS-CoV-2. JAMA 2020; 6; https://doi.org/10.1001/jama.2020.8259.