Infection with SARS-CoV-2 following Second Dose Pfizer-BioNTech mRNA COVID-19 Vaccine BNT162b2 in Danish Adolescents Aged 12–18 Years: A Real-World Nationwide Danish Cohort Study
Nina Marie Birk,
Anne Vinggaard Christensen,
Ulrikka Nygaard,
Henning Bundgaard,
Susanne Dam Nielsen,
Selina Kikkenborg Berg,
Helle Wallach-Kildemoes
Affiliations
Nina Marie Birk
Department of Cardiology, Copenhagen University Hospital Rigshospitalet, Inge Lehmanns Vej 7, 2100 Copenhagen, Denmark
Anne Vinggaard Christensen
Department of Cardiology, Copenhagen University Hospital Rigshospitalet, Inge Lehmanns Vej 7, 2100 Copenhagen, Denmark
Ulrikka Nygaard
Faculty of Health and Medical Sciences, University of Copenhagen, Blegdamsvej 3B, 2200 Copenhagen, Denmark
Henning Bundgaard
Department of Cardiology, Copenhagen University Hospital Rigshospitalet, Inge Lehmanns Vej 7, 2100 Copenhagen, Denmark
Susanne Dam Nielsen
Department of Infectious Diseases, Copenhagen University Hospital Rigshospitalet, Blegdamsvej 9, 2100 Copenhagen, Denmark
Selina Kikkenborg Berg
Department of Cardiology, Copenhagen University Hospital Rigshospitalet, Inge Lehmanns Vej 7, 2100 Copenhagen, Denmark
Helle Wallach-Kildemoes
Department of Cardiology, Copenhagen University Hospital Rigshospitalet, Inge Lehmanns Vej 7, 2100 Copenhagen, Denmark
In this real-world cohort study based on Danish nationwide registers, the cumulated proportion, relative risk (RR) of SARS-CoV-2 breakthrough infections, and vaccine effectiveness (VE) were investigated in adolescents aged 12–18 years following vaccination with the BNT162b2 vaccine compared to unvaccinated controls. Adolescents with and without vaccination with the first dose of BNT162b2 between 1 May and 30 September 2021 were included. Effect estimates include proportions with a positive SARS-CoV-2 RT-PCR test among vaccinated and unvaccinated, RR, and VE at three different time points. During Delta-dominance, VE was first 97.6% (95% CI 96.3–98.4), then 96.2% (95% CI 95.4–96.9) in the age group 12–15 and 95.1% (95% CI 94.1–96.0) followed by 95.5% (95% CI 94.8–96.1) in the age group 16–18 years, respectively. During Omicron dominance, VE was 5.8% (95% CI 4.6–7.0) in ages 12–15 years and 9.2% (95% CI 7.7–10.6) in ages 16–18 years. Thus, BNT162b2-vaccine protection was limited during the Omicron era.