Cohort study of Covid-19 vaccine effectiveness among healthcare workers in Finland, December 2020 - October 2021

Vaccine. 2022 Jan 31;40(5):701-705. doi: 10.1016/j.vaccine.2021.12.032. Epub 2021 Dec 18.

Abstract

Recently, Covid-19 vaccine effectiveness has decreased especially against mild disease due to emergence of the Delta variant and waning protection. In this register-based study among healthcare workers in Finland, the vaccine effectiveness of two-dose mRNA vaccine series against SARS-CoV-2 infection decreased from 82% (95% CI 79-85%) 14-90 days after vaccination to 53% (43-62%) after 6 months. Similar trend was observed for other series. Waning was not observed against Covid-19 hospitalization. These results facilitate decision-making of booster doses for healthcare workers.

Keywords: Covid-19 hospitalization; Healthcare workers; SARS-CoV-2 infection; Vaccine effectiveness; Waning.

MeSH terms

  • BNT162 Vaccine
  • COVID-19 Vaccines*
  • COVID-19*
  • Cohort Studies
  • Finland / epidemiology
  • Health Personnel
  • Humans
  • SARS-CoV-2
  • Vaccine Efficacy
  • Vaccines, Synthetic
  • mRNA Vaccines

Substances

  • COVID-19 Vaccines
  • Vaccines, Synthetic
  • mRNA Vaccines
  • BNT162 Vaccine

Supplementary concepts

  • SARS-CoV-2 variants