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Longitudinal assessment of SARS-CoV-2 IgG seroconversionamong front-line healthcare workers during the first wave of the Covid-19 pandemic at a tertiary-care hospital in Chile

  • Iruretagoyena, Mirentxu1, 2
  • Vial, Macarena R.2
  • Spencer-Sandino, Maria3, 4
  • Gaete, Pablo2
  • Peters, Anne3, 4
  • Delgado, Iris2, 3
  • Perez, Inia2
  • Calderon, Claudia2
  • Porte, Lorena1, 2
  • Legarraga, Paulette1, 2
  • Anderson, Alicia1, 2
  • Aguilera, Ximena2, 3
  • Vial, Pablo2, 3
  • Weitzel, Thomas1, 2, 3
  • Munita, Jose M.2, 3, 4
  • 1 Clínica Alemana de Santiago, Santiago, Chile , Santiago (Chile)
  • 2 Universidad del Desarrollo (CAS-UDD), Santiago, Chile , Santiago (Chile)
  • 3 Facultad de Medicina CAS-UDD, Santiago, Chile , Santiago (Chile)
  • 4 Millennium Initiative for Collaborative Research on Bacterial Resistance (MICROB-R), Santiago, Chile , Santiago (Chile)
Published Article
BMC Infectious Diseases
Springer (Biomed Central Ltd.)
Publication Date
May 26, 2021
DOI: 10.1186/s12879-021-06208-2
Springer Nature


BackgroundHealthcare workers (HCWs) are at high risk of exposure to SARS-CoV-2. Cross-sectional studies have provided variable rates of seroprevalence in HCWs. Longitudinal assessments of the serological response to Covid-19 among HCWs are crucial to understanding the risk of infection and changes in antibody titers over time. We aimed to investigate seroprevalence and risk factors associated with seroconversion in a prospective cohort of HCWs during the peak of the first wave of the Covid-19 pandemic.MethodsWe conducted a longitudinal study among 446 front-line HCWsin a tertiary-care hospital in Chile from April to July 2020. IgG was determined monthly using two different ELISAs in serum samples of HCWs, during the three-month period. In each visit, demographic data, symptoms, risk factors, and exposure risks were also assessed.ResultsThe overall seroprevalence at the end of the study period was 24% (95% CI20.2–28.3), with 43% of seropositive HCWs reporting no prior symptoms. Seroconversion rates significantly differed over the study period, from 2.1% to as high as 8.8% at the peak of the epidemic. There were no statistically significant differences observed between HCWs in direct clinical care of patients with Covid-19 and those working in low risk areas. Antibody titers appeared to wane over time.ConclusionsHCWs were severely affected with a high rate of seroconversion that appeared to mirror the local epidemiological situation. A significant amount of participants underwent an asymptomatic infection, highlighting the need for improved surveillance policies. Antibody titers appear to wane over time; further studies to understand this finding’s impact on the risk of reinfection are warranted.

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