Monovalent mRNA XBB.1.5 vaccine effectiveness against COVID-19 hospitalization in Quebec, Canada: impact of variant replacement and waning protection during 10-month follow-up

Publication date: Nov 12, 2024

Background. We evaluated mRNA COVID-19 vaccine effectiveness (VE) for the XBB.1.5 formulation against COVID-19 hospitalizations among adults aged [≥]60 years during a ten-month follow-up period. Methods. We conducted a test-negative case-control study using Quebec population-based administrative data. Specimens collected from individuals aged [≥]60 years tested at an acute-care hospital from October 2023 to August 2024 were considered test-positive cases if hospitalized for COVID-19, or controls if test-negative for SARS-CoV-2. Vaccination was defined by receipt of at least one mRNA XBB-vaccine (autumn or spring) dose. Multivariate logistic regression analyses estimated VE relative to several comparator groups, primarily those last-vaccinated in 2022, by subvariant predominant period (XBB, JN and KP), by time since XBB-vaccination and by number of XBB-vaccine doses (KP period). Results. Participants overall and by XBB, JN and KP periods included: 5532 (4.9%) test-positive cases (1321, 1838 and 1372, respectively) and 108473 (95.1%) test-negative controls (12881, 53414 and 28595, respectively); 14584 specimens were collected during periods of subvariant cocirculation. By subvariant period, 3322 (25.8%), 27041 (50.6%) and 15401 (53.9%) controls, respectively, were considered XBB-vaccinated. Overall VE was 30% (95%CI:24-35) and by XBB, JN or KP period: 54% (95%CI:46-62), 23% (95%CI:13-32) and 0% (95%CI:-18-15), respectively. During each subvariant period, the hospitalization risk was reduced only during the first four months post-vaccination. Conclusions. Among individuals aged [≥]60 years, mRNA XBB-vaccination provided meaningful, albeit limited and short-term, protection against COVID-19 hospitalization due to XBB, JN and KP subvariants in. Better vaccines are needed to effectively reduce COVID-19 disease burden.

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Concepts Keywords
24317190doi Canada
August Covid
Canada Individuals
December Mrna
Hospitalizations Negative
Period
Preprint
Quebec
Specimens
Subvariant
Subvariants
Test
Vaccination
Vaccine
Xbb

Semantics

Type Source Name
disease MESH COVID-19
drug DRUGBANK Pentaerythritol tetranitrate
drug DRUGBANK Tropicamide
drug DRUGBANK Diethylstilbestrol
disease MESH Influenza
disease IDO nucleic acid
disease MESH emergency
disease MESH infection

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