Low rate of COVID-19 seroconversion in health-care workers at a Department of Infectious Diseases in Sweden during the later phase of the first wave; a prospective longitudinal seroepidemiological study

Abstract

Background: Health-care workers are at risk of contracting and transmitting SARS-CoV-2. The aim of this study was to investigate the prevalence of SARS-CoV-2 IgG antibodies and the rate of seroconversion in an environment with high exposure to SARS-CoV-2. Methods: 131 health-care workers at the Department of Infectious Diseases in V€ asterås, Sweden, were included in the study. Abbott's SARS-COV-2 IgG immunoassay was used with a signal cutoff ratio of !1.4. Every third week from the beginning of May, blood samples were drawn, and the participants completed a questionnaire regarding symptoms consistent with COVID-19 and the result of any SARS-CoV-2 PCR performed since the last sampling occasion. Participants with IgG antibodies against SARS-CoV-2 were re-sampled only on the sixth and last occasion. Results: At the start of the study, 18 (15%) participants had SARS-CoV-2 IgG antibodies. At the end, 25 (19%) of 131 participants were seropositive. One case of asymptomatic infection was detected, and two cases with PCR-confirmed COVID-19 did not develop IgG antibodies. Conclusion: The low rate of seroconversion during the study suggests that it is possible to prevent transmission of SARS-COV-2 in a high-exposure environment. Compliance with adequate infection control guidelines is the likely explanation of our findings.

SARS-CoV-2 serostatus of healthcare worker in the Austrian state Vorarlberg between June 2020 and January 2021

“…One of the highest incidence rates of COVID-19 infections in the world were seen in the U.S., with and a seroprevalence rate of 19% in the general population (27) and 27% in HCW at the New York City Hospital South Bronx at the same time (28). Almost similar rates were found in HCW in Sweden (19%) (29) and some parts of the U.K. namely London (32%) (30) and Birmingham (24%) (31). Nevertheless, these rates are still below the seropositivity rate of 67%, which has initially been estimated as threshold for community immunity against SARS-CoV-2 (32) and now has been estimated to be as high as 85% according to CDC (33).…”

Screening and Confirmatory Testing for SARS-CoV-2 Antibodies: Comparison of Health and Non-Health Workers in a Nationwide Healthcare Organization in Central Europe

“…Thus, a longer period of observation may show different results. In most seroprevalence studies, an appropriate control group is absent [ 32 ]. An important feature of our study design was the inclusion of a control group of working adults, which allowed for comparison of HCW with non-HCW.…”

Seroprevalencia y seguimiento de anticuerpos IgG contra SARS-CoV-2 en personal del Laboratorio Estatal de Salud Pública de Guanajuato LaESaP

“…La seroprevalencia reportada en otros estudios realizados en personal de salud varía de acuerdo al país y tipo de institución considerablemente. Mulki Rashid y col., reportan una seroprevalencia del 15% en el personal que labora en el Departamento de Enfermedades Infecciosas en Vasteras, Suecia (Rashid-Abdi et al, 2020). William B. Stubblefield y col., reporta en su estudio realizado al personal de salud del Vanderbilt University Medical Center, en Nashville, Estados Unidos, durante el primer mes de atención a pacientes COVID-19, una seroprevalencia del 7.6% (Stubblefield et al, 2020).…”

“…Otros estudios analizan el tiempo promedio de seroconversión de los pacientes con rRT-PCR positiva (Wajnberg et al, 2020) y cuáles son los pacientes que no desarrollan anticuerpos IgG detectables a pesar de tener una rRT-PCR positiva (Marklund et al, 2020). Mulki-Rashid y col., realizaron un estudio en Suecia que incluyó 131 trabajadores de salud y obtuvieron al primer corte del estudio un 15% de prevalencia de anticuerpos IgG contra SARS CoV-2 por quimioluminiscencia (Rashid-Abdi et al, 2020). Venugopal y col. realizaron un estudio en un hospital en Nueva York donde se encontró una seroprevalencia del 27% en los trabajadores de salud (Venugopal et al, 2020).…”