TY - JOUR
T1 - Seroprevalence of SARS-CoV-2 antibodies and reduced risk of reinfection through 6 months
T2 - a Danish observational cohort study of 44,000 healthcare workers
AU - Iversen, Kasper
AU - Kristensen, Jonas Henrik
AU - Hasselbalch, Rasmus Bo
AU - Pries-Heje, Mia
AU - Nielsen, Pernille Brok
AU - Knudsen, Andreas Dehlbæk
AU - Fogh, Kamille
AU - Norsk, Jakob Boesgaard
AU - Andersen, Ove
AU - Fischer, Thea Køhler
AU - Juul Jensen, Claus Antonio
AU - Torp-Pedersen, Christian
AU - Rungby, Jørgen
AU - Ditlev, Sisse Bolm
AU - Hageman, Ida
AU - Møgelvang, Rasmus
AU - Gybel-Brask, Mikkel
AU - Dessau, Ram B
AU - Sørensen, Erik
AU - Harritshøj, Lene
AU - Folke, Fredrik
AU - Sten, Curt
AU - Engel Møller, Maria Elizabeth
AU - Benfield, Thomas
AU - Ullum, Henrik
AU - Jørgensen, Charlotte Sværke
AU - Erikstrup, Christian
AU - Ostrowski, Sisse R
AU - Nielsen, Susanne Dam
AU - Bundgaard, Henning
N1 - Copyright © 2021. Published by Elsevier Ltd.
PY - 2022/5
Y1 - 2022/5
N2 - OBJECTIVES: Antibodies to severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) are a key factor in protecting against coronavirus disease 2019 (COVID-19). We examined longitudinal changes in seroprevalence in healthcare workers (HCWs) in Copenhagen and the protective effect of antibodies against SARS-CoV-2.METHODS: In this prospective study, screening for antibodies against SARS-CoV-2 (ELISA) was offered to HCWs three times over 6 months. HCW characteristics were obtained by questionnaires. The study was registered at ClinicalTrials.gov, NCT04346186.RESULTS: From April to October 2020 we screened 44 698 HCWs, of whom 2811 were seropositive at least once. The seroprevalence increased from 4.0% (1501/37 452) to 7.4% (2022/27 457) during the period (p < 0.001) and was significantly higher than in non-HCWs. Frontline HCWs had a significantly increased risk of seropositivity compared to non-frontline HCWs, with risk ratios (RRs) at the three rounds of 1.49 (95%CI 1.34-1.65, p < 0.001), 1.52 (1.39-1.68, p < 0.001) and 1.50 (1.38-1.64, p < 0.001). The seroprevalence was 1.42- to 2.25-fold higher (p < 0.001) in HCWs from dedicated COVID-19 wards than in other frontline HCWs. Seropositive HCWs had an RR of 0.35 (0.15-0.85, p 0.012) of reinfection during the following 6 months, and 2115 out of 2248 (95%) of those who were seropositive during rounds one or two remained seropositive after 4-6 months. The 133 of 2248 participants (5.0%) who seroreverted were slightly older and reported fewer symptoms than other seropositive participants.CONCLUSIONS: HCWs remained at increased risk of infection with SARS-CoV-2 during the 6-month period. Seropositivity against SARS-CoV-2 persisted for at least 6 months in the vast majority of HCWs and was associated with a significantly lower risk of reinfection.
AB - OBJECTIVES: Antibodies to severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) are a key factor in protecting against coronavirus disease 2019 (COVID-19). We examined longitudinal changes in seroprevalence in healthcare workers (HCWs) in Copenhagen and the protective effect of antibodies against SARS-CoV-2.METHODS: In this prospective study, screening for antibodies against SARS-CoV-2 (ELISA) was offered to HCWs three times over 6 months. HCW characteristics were obtained by questionnaires. The study was registered at ClinicalTrials.gov, NCT04346186.RESULTS: From April to October 2020 we screened 44 698 HCWs, of whom 2811 were seropositive at least once. The seroprevalence increased from 4.0% (1501/37 452) to 7.4% (2022/27 457) during the period (p < 0.001) and was significantly higher than in non-HCWs. Frontline HCWs had a significantly increased risk of seropositivity compared to non-frontline HCWs, with risk ratios (RRs) at the three rounds of 1.49 (95%CI 1.34-1.65, p < 0.001), 1.52 (1.39-1.68, p < 0.001) and 1.50 (1.38-1.64, p < 0.001). The seroprevalence was 1.42- to 2.25-fold higher (p < 0.001) in HCWs from dedicated COVID-19 wards than in other frontline HCWs. Seropositive HCWs had an RR of 0.35 (0.15-0.85, p 0.012) of reinfection during the following 6 months, and 2115 out of 2248 (95%) of those who were seropositive during rounds one or two remained seropositive after 4-6 months. The 133 of 2248 participants (5.0%) who seroreverted were slightly older and reported fewer symptoms than other seropositive participants.CONCLUSIONS: HCWs remained at increased risk of infection with SARS-CoV-2 during the 6-month period. Seropositivity against SARS-CoV-2 persisted for at least 6 months in the vast majority of HCWs and was associated with a significantly lower risk of reinfection.
U2 - 10.1016/j.cmi.2021.09.005
DO - 10.1016/j.cmi.2021.09.005
M3 - Article
C2 - 34543759
SN - 1198-743X
VL - 28
SP - 710
EP - 717
JO - Clinical Microbiology and Infection
JF - Clinical Microbiology and Infection
IS - 5
ER -