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Published on: September 8, 2023
Vaccine effectiveness against infection with the Delta (B.1.617.2) variant, Norway, April to August 2021
Elina Seppälä1,2, Lamprini Veneti3, Jostein Starrfelt3
1Department of infectious disease control and vaccines, Norwegian Institute of Public Health, Oslo, Norway.
Abstract:
Some variants of SARS-CoV-2 are associated with increased transmissibility, increased disease severity or decreased vaccine effectiveness (VE). In this population-based cohort study (n = 4,204,859), the Delta variant was identified in 5,430 (0.13%) individuals, of whom 84 were admitted to hospital. VE against laboratory confirmed infection with the Delta variant was 22.4% among partly vaccinated (95% confidence interval (CI): 17.0-27.4) and 64.6% (95% CI: 60.6-68.2) among fully vaccinated individuals, compared with 54.5% (95% CI: 50.4-58.3) and 84.4% (95%CI: 81.8-86.5) against the Alpha variant.
