SARS-CoV-2 Seroprevalence Among All Workers in a Teaching Hospital in Spain: Unmasking The Risk

Abstract

Background: Health-care workers (HCW) are at increased risk for SARS-CoV-2 infection, but few studies have evaluated prevalence of antibodies against SARS-CoV-2 among them. Objective: To determine the seroprevalence against SARS-CoV-2 in all HCW. Methods. Cross-sectional study (April 14th- 27th , 2020) of all HCW at Hospital Universitario Fundacion Alcorcon, a second level teaching hospital in Madrid, Spain. SARS-CoV-2 IgG was measured by ELISA. HCW were classified by professional category, working area, and risk for SARS-CoV-2 exposure. Results: Among 2919 HCW, 2590 (90.5%) were evaluated. Mean age was 43.8 years (SD 11.1) and 73.9% were females. Globally, 818 (31.6%) workers were IgG positive, with no differences for age, sex or previous diseases. Among them, 48.5% did not report previous symptoms. Seropositivity was more frequent in high (33.1%) and medium (33.8%) than in low-risk areas (25.8%, p=0.007), but no difference was found for hospitalization areas attending COVID-19 and non-COVID-19 patients (35.5 vs 38.3% p=NS). HCW with a previous SARS-CoV2 PCR positive test were IgG seropositive in 90.8%. By multivariate logistic regression analysis, seropositivity was associated with being physicians (OR 2.37, CI95% 1.61-3.49), nurses (OR 1.67, CI95% 1.14-2.46), or nurse- assistants (OR 1.84, CI95% 1.24-2.73), HCW working at COVID-19 hospitalization areas (OR 1.71, CI95% 1.22-2.40), non-COVID-19 hospitalization areas (OR 1.88, CI95% 1.30-2.73), and at the Emergency Room (OR 1.51, CI95% 1.01-2.27) Conclusions: Seroprevalence uncovered a high rate of infection previously unnoticed among HCW. Patients not suspected of having COVID-19 as well as asymptomatic HCW may be a relevant source for nosocomial SARS-CoV-2 transmission.

Differential occupational risks to healthcare workers from SARS-CoV-2 observed during a prospective observational study

“…A voluntary asymptomatic screening programme offering SARS-CoV-2 PCR and antibody testing to all staff working anywhere on site commenced on 23 rd April 2020. Between 23 rd April and 8th June, 10,610 of the 13,800 (77%) staff employed by OUH registered for asymptomatic testing and 10,034 (73%) were tested at least once, 9926 by PCR and 9958 by serology. The majority of testing was undertaken in the first three weeks of May 2020 ( Figure 1C).…”

“…However, crucial to designing a safe working environment and maintaining effective healthcare services is an understanding of the risks associated with specific roles and to individuals, and whether risk is associated with social-mixing, direct exposure to Covid-19 patients or PPE type. Some studies have suggested exposure to Covid-19 patients poses increased risk ( Nguyen et al, 2020 ; Ran et al, 2020 ; Lombardi et al, 2020 ), whilst others have not ( Hunter et al, 2020 ; Galan et al, 2020 ; Folgueira et al, 2020 ). However, none have addressed these questions by comprehensively investigating all staff groups across an institution, simultaneously assessing symptomatic and asymptomatic incidence.…”

Does Working in a COVID-19 Receiving Health Facility Influence Seroprevalence to SARS-CoV-2?

“…As reported during the SARS-CoV-1 epidemic, HCWs working in SARS medical wards had higher seroprevalence than those working in general medical wards [18]. Moreover, it is only common-sensical to assume that HCWs working in COVID-19 receiving facilities will be at a higher risk to contract COVID- 19. Surprisingly, the frequency of positive SARS-CoV-2 antibodies for the non-COVID-19 receiving hospital was 32.7% as compared to 28.2% in COVID-19 receiving hospital (p=0.129).…”

“…It has been reported during the second phase of the epidemic in China that among the 42,600 HCWs who were deployed in Hubei province to serve the COVID-19 cases, none were infected with SARS-CoV-2 [9]. In contrast, it has been reported from Spain that seroprevalence of SARS-CoV-2 was less frequent (25.8%) in low-risk areas as compared to medium-(33.8%) and high-risk areas (33.1%) (p=0.007) [19]. The findings of the Spanish study could be attributed to the fact that it was conducted only in COVID-19 receiving hospitals with no comparison made with a non-COVID-19 receiving hospital.…”

“…A sample size of 1,051 was arrived at by using the WHO sample size calculator, assuming a prevalence rate of 33.8% [19], a confidence level of 95%, a margin of error of 3%, and an addition of 10% to compensate for the loss to follow-up. Using the non-proportionate stratified random sampling, 1,051 HCWs (469 from hospital 'A' and 582 from hospital 'B') were approached for participation in the study.…”