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 2026 Open access

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Authors: Sylvia Aponte-Hao, Huong Luu, Karen J. B. Martins, Jason R. Randall, Lynora M. Saxinger, Elissa Rennert‐May, Jenine R. Leal, Tyler S. Williamson, Amanda Wilson, Michelle Emery Blake, Tianyi Lu, Shehzad M. Iqbal
+4 more James A. Mansi, André Brandão de Araújo, David Martin, Scott W Klarenbach
DOI: 10.1371/journal.pone.0354822
Cited by: 1
References: 23

Abstract

BACKGROUND: With a large proportion of adults in Canada vaccinated against SARS-CoV-2, it is important to identify who remain at risk for severe COVID-19 outcomes after primary vaccination and additional (booster) doses. METHODS: Adults (≥18 years) who received at least a primary vaccination schedule between December 2020 and March 2023 in Alberta, Canada were identified through population-level administrative data. Factors associated with severe COVID-19 outcomes (COVID-19 related hospitalization or death) were examined using univariable and multivariable Cox proportional hazard models. RESULTS: Among those who received a primary vaccination schedule (n = 2,639,731), 0.2% (n = 5,475) had ≥ 1 severe COVID-19 outcome. Factors associated with a greater risk of a severe COVID-19 outcome included older age (≥65 versus

Fields of Study & Subjects

Vaccine Coverage and Hesitancy SARS-CoV-2 and COVID-19 Research COVID-19 Impact on Reproduction

Publication details

Journal / source
PLoS ONE
Publisher
Public Library of Science (PLoS)
Volume
21
Issue
8
Pages
e0354822–e0354822
Publication date
17 August 2026
Language
EN