Study registration: *
Publication Nasreen S, medRxiv, 2021
Dates: 2020-12-14 to 2021-08-17
Funding: Public/non profit (Canadian Immunization Research Network (CIRN) through a grant from the Public Health Agency of Canada and the Canadian Institutes of Health Research (CNF 151944). Public Health Agency of Canada, through the Vaccine Surveillance Reference group and the COVID-19 Immunity Task Force. ICES, which is funded by an annual grant from the Ontario Ministry of Health (MOH).)
Conflict of interest: Yes (KW is CEO of CANImmunize and serves on the data safety board for the Medicago COVID-19 vaccine trial.)

Methods

Study design:Test-negative
Description of participants: Symptomatic community-dwelling individuals aged ≥16 years with no history of SARS-CoV-2 infection in Ontario, Canada
Inclusion criteria:
  • Community-dwelling individuals
  • aged ≥16 years
  • had symptoms consistent with or a severe outcome attributable to COVID-19
  • assessed between January 11 to August 17, 2021
  • in Ontario, Canada.

Exclusion criteria:
  • Individuals who tested positive for SARS-CoV-2 prior to their selected index date.

Follow-up duration (months): 8.20
Vaccines:
  • 1 or 2 doses of BNT162b2
  • 1 or 2 doses of ChAdOx1-S
  • 1 or 2 doses of mRNA-1273
Variant description :
Variant name: Beta/Gamma
Evidence: Direct evidence (effectiveness determined by sequencing cases)
Documents
available

Protocol

NR

Statistical plan

NR

Data-sharing stated: Yes, The full dataset creation plan and underlying analytic code are available from the authors upon request
Data accessibility: www.ices.on.ca/DAS (email: das@ices.on.ca)
General comment Control for confounding was good but uncontrolled confounding cannot be ruled out; in addition there is a possibility of selection bias (particularly for the outcome severe disease), due to uncertainties over the validity of a test-negative design in this regard.