Study registration: *
Publication Seppala E, Euro Surveill, 2021
Dates: 2020-12-27 to 2021-08-15
Funding: No specific funding (No specific funding received. The study was performed as part of routine work at the Norwegian Institute of Public Health.)
Conflict of interest: no COI (None declared.)

Methods

Study design:Cohort
Description of participants: All adults aged 18 years or older with no prior SARS-CoV-2 infection with a national identification number registered in multiple centres in Norway
Inclusion criteria:
  • All adults aged 18 years or older
  • with a national identification number registered in Norway
  • with data from 15 April to 15 August 2021.

Exclusion criteria:
  • prior SARS-CoV-2 infection
  • those with an interval between first and second dose of a COVID-19 vaccine that did not adhere to national recommendations (recommended time between doses is 12 weeks with minimum 21 days for Comirnaty/BioNTech-Pfizer and 12 weeks with minimum 28 days for Spikevax/mRNA-1273 Moderna for immunocompetent individuals
  • while for immunocompromised recommended interval is 3 and 4 weeks, respectively).

Follow-up duration (months): 7.70
Vaccines:
  • 1 or 2 doses of either BNT162b2 or mRNA-1273, at least 21 days apart
Variant description :
Variant name: Delta
Evidence: Direct evidence (effectiveness determined by sequencing cases)
Documents
available

Protocol

NR

Statistical plan

NR

Data-sharing stated: NR
Data accessibility: NR
General comment In addition to the published report, the supplementary material was used in data extraction and risk of bias assessment. 81% received Pfizer vaccine alone. Unclear whether vaccination status was assessed at time of infection (censoring) or study end (Table 1 & Supplement, Part 2).