Incidence and risk factors of SARS-CoV-2 infection among workers in a public health laboratory in Tunisia

Archives of Virology (2023) 168:69 https://doi.org/10.1007/s00705-022-05636-y ORIGINAL ARTICLE Incidence and risk factors of SARS‑CoV‑2 infection among workers in a public health laboratory in Tunisia Ghassen Kharroubi1,2 · Ines Cherif1,2 · Wissem Ghawar1,2 · Nawel Dhaouadi1 · Rihab Yazidi1,2 · Sana Chaabane1,2 · Mohamed Ali Snoussi1,2 · Sadok Salem1,2 · Wafa Ben Hammouda2 · Sonia Ben Hammouda2 · Adel Gharbi1,2 · Nabil Bel Haj Hmida1,2 · Samia Rourou3 · Koussay Dellagi2,4 · Mohamed‑Ridha Barbouche2 · Chaouki Benabdessalem2 · Melika Ben Ahmed2 · Jihène Bettaieb1,2 Received: 3 June 2022 / Accepted: 15 September 2022 © The Author(s), under exclusive licence to Springer-Verlag GmbH Austria, part of Springer Nature 2023 Abstract The aim of this study was to measure the extent of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection among workers at the Institut Pasteur de Tunis (IPT), a public health laboratory involved in the management of the COVID-19 pandemic in Tunisia, and to identify risk factors for infection in this occupational setting. A cross-sectional survey was conducted on IPT workers not vaccinated against coronavirus disease 2019 (COVID-19). Participants completed a questionnaire that included a history of reverse transcription-polymerase chain reaction (RT-PCR)-confirmed SARS-CoV-2 infection. Immunoglobulin G antibodies against the receptor-binding domain of the spike antigen (anti-S-RBD IgG) and the nucleocapsid protein (anti-N IgG) of the SARS-CoV-2 virus were detected by enzyme-linked immunoassay (ELISA). A multivariate analysis was used to identify factors significantly associated with SARS-CoV-2 infection. A total of 428 workers were enrolled in the study. The prevalence of anti-S-RBD and/or anti-N IgG antibodies was 32.9% [28.7–37.4]. The cumulative incidence of SARS-CoV-2 infection (positive serology and/or previous positive RT-PCR test) was 40.0% [35.5–44.9], while the proportion with asymptomatic infection was 32.9%. One-third of the participants with RT-PCR-confirmed infection tested seronegative more than 90 days postinfection. Participants aged over 40 and laborers were more susceptible to infection (adjusted OR [AOR] = 1.65 [1.08–2.51] and AOR = 2.67 [1.45–4.89], respectively), while tobacco smokers had a lower risk of infection (AOR = 0.54 [0.29–0.97]). The SARS-CoV-2 infection rate among IPT workers was not significantly different from that detected concurrently in the general population. Hence, the professional activities conducted in this public health laboratory did not generate additional risk to that incurred outside the institute in day-to-day activities. Keywords Health care workers · SARS-CoV-2 infection · Seroprevalence · Risk factors Introduction Handling Editor: William G. Dundon. * Jihène Bettaieb 1 Department of Medical Epidemiology, Institut Pasteur de Tunis, University of Tunis El Manar, 13 Place Pasteur BP‑74, 1002 Tunis Belvedere, Tunisia 2 Laboratory of Transmission, Control and Immunobiology of Infections (LR11IPT02), Institut Pasteur de Tunis, University of Tunis El Manar, Tunis, Tunisia 3 Laboratory of Molecular Microbiology, Vaccinology and Biotechnology Development, Institut Pasteur de Tunis, University of Tunis El Manar, Tunis, Tunisia 4 Pasteur Network, Institut Pasteur, Paris, France Health care workers (HCWs), especially those in contact with and/or who care for coronavirus disease 2019 (COVID19) patients, have an increased risk of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection compared to the general population [1]. Data collected by the World Health Organization (WHO) during the early stages of the pandemic, primarily from European and American countries, indicated that nearly 14% of COVID-19 cases were among health workers [1]. These figures were mainly based on reverse transcription polymerase chain reaction (RT-PCR) testing and most likely underestimated the true extent of infection. In fact, many infected people are asymptomatic or only express minor symptoms and therefore do 13 Vol.:(0123456789) 69 Page 2 of 10 not get tested [2]. Thus, it is necessary to estimate the invisible ‘iceberg’ of mild infections to assess the real burden of SARS-CoV-2 infections [3]. Seroepidemiological studies are key to understanding the extent of infection in a population. However, uncertainties in estimates may be related to test performance or the proportion of infected persons who do not develop antibodies or whose antibody levels fall under the cutoff value at the time of testing [4–7]. The real extent of SARS-CoV-2 infection could be better estimated by measuring the cumulative incidence of infection based on serology and RT-PCR testing, a goal mainly jeopardized by the unavailability of mass testing in countries that lack resources. Institut Pasteur de Tunis (IPT) is a scientific research institution focused on human health that is primarily involved in the investigation of infectious diseases. Public health laboratory activities and diagnostic tests for outpatients are also performed at the institute. IPT has been involved in the surveillance and monitoring of the COVID19 pandemic in Tunisia since its inception, by establishing a protocol for the molecular diagnosis of SARS-CoV-2 infection. This has resulted in a heavy workload, with many IPT staff members volunteering to help the virology department by collecting nasopharyngeal swabs from consultants and travelers, managing the sample circuit, and performing RTPCR testing. Therefore, a committee was appointed within IPT to monitor and mitigate the risk of infection among staff members. A nasal swab RT-PCR test is offered to any person presenting symptoms suggestive of COVID-19 or having had contact with a positive case, and the test is repeated periodically in some departments of IPT. Although many cases of SARS-CoV-2 infection have been detected among IPT staff, even in those not involved in COVID-19 activities, the actual degree of spread of the infection among the workforce is unknown. The aims of this study were to use PCR and serology to measure the cumulative incidence of SARS-CoV-2 among IPT staff from the start of the pandemic in Tunisia (March 2020) until the end of the second wave and the start of the third wave in the country (March 2021), to determine the proportion of asymptomatic infections, and to study risk factors for infection. Materials and methods Study design and study population A cross-sectional survey was conducted during the last two weeks of March 2021, which coincided with the end of the second wave of the COVID-19 pandemic in Tunisia and the start of the third wave, prior to widespread vaccination among HCWs in the country. All IPT staff and PhD students 13 G. Kharroubi et al. who had not received the COVID-19 vaccine were invited to participate in the survey. All Pasteurian community members with an institutional email address were informed of the study objectives and modality o (...truncated)