Factors associated with severe COVID-19 outcomes among adults with at least a primary vaccination schedule: A retrospective cohort study from Alberta, Canada
PLOS One·
- DOI
- 10.1371/journal.pone.0354822
- PMID
- —
- PMCID
- —
- OpenAlex
- W4413480736
- Study type
- Cohort study
- Publisher
- Public Library of Science (PLoS)
- Article type
- journal-article
- Integrity
- current
Why this research matters now
The findings can inform decision-making, public health strategies, and policy development to protect vaccinated populations at elevated risk. The results support recommendations from Canada's National Advisory Committee on Immunisation for specific groups to remain current with COVID-19 vaccination to reduce severe outcomes.
Structured evidence summary
Research question
The study aimed to identify factors associated with severe COVID-19 outcomes (hospitalization or death) among adults who received at least a primary COVID-19 vaccination schedule.
Study design
Retrospective cohort study using population-level administrative data. Univariable and multivariable Cox proportional hazard models were used to examine associations between patient factors and severe outcomes.
Population and setting
Adults aged 18 years and older who received at least a primary COVID-19 vaccination schedule between December 2020 and March 2023 in Alberta, Canada. The cohort included 2,639,731 individuals, with a subset of 1,580,110 receiving at least one additional dose.
Main findings
Among primary-vaccinated adults, 0.2% experienced severe COVID-19 outcomes. Older age (≥65 years: unadjusted HR 8.83), higher comorbidity burden (severe burden: unadjusted HR 32.56), specific health conditions including cardiovascular disease (unadjusted HR 7.01) and dementia (unadjusted HR 13.96), and male sex (unadjusted HR 1.07) were associated with increased risk. These associations remained significant in adjusted models and among those receiving additional doses.
Public-health relevance
The findings can inform decision-making, public health strategies, and policy development to protect vaccinated populations at elevated risk. The results support recommendations from Canada's National Advisory Committee on Immunisation for specific groups to remain current with COVID-19 vaccination to reduce severe outcomes.
Important limitations
This summary is limited to the supplied single-article abstract and metadata. The original paper is required for decision-grade interpretation, including assessment of confounding adjustment, missing data handling, outcome ascertainment methods, and generalizability beyond Alberta.
GIDS interpretation
The classifier links indicate this article is discoverable through queries related to COVID-19, SARS, Canada, health policy, and vaccination. These tags reflect the study's subject matter and geographic scope, supporting retrieval in literature surveillance systems focused on vaccine effectiveness and pandemic response policy.
Related GIDS surveillance
Literature context does not validate, explain, or change a surveillance signal. Exact and contextual relationships are shown separately.
Evidence relationships
This article has 10 auditable classifier relationships to diseases, places, topics, and study design.