Vaccine effectiveness against SARS-CoV-2 infection or COVID-19 hospitalization with the Alpha, Delta, or Omicron SARS-CoV-2 variant: A nationwide Danish cohort study.
Mie Agermose GramHanne-Dorthe EmborgAstrid Blicher ScheldeNikolaj Ulrik FriisKatrine Finderup NielsenIda Rask Moustsen-HelmsRebecca LegarthJanni Uyen Hoa LamManon ChaineAisha Zahoor MalikMorten RasmussenJannik FonagerRaphael Niklaus SieberMarc SteggerSteen EthelbergPalle Valentiner-BranthChristian Holm HansenPublished in: PLoS medicine (2022)
Two vaccine doses provided high protection against SARS-CoV-2 infection and COVID-19 hospitalization with the Alpha and Delta variants with protection, notably against infection, waning over time. Two vaccine doses provided only limited and short-lived protection against SARS-CoV-2 infection with Omicron. However, the protection against COVID-19 hospitalization following Omicron SARS-CoV-2 infection was higher. The third vaccine dose substantially increased the level and duration of protection against infection with the Omicron variant and provided a high level of sustained protection against COVID-19 hospitalization among the +60-year-olds.