Effectiveness of 2024/25 KP.2 Vaccine Against Outpatient COVID‐19 in Canada

Influenza and Other Respiratory Viruses 2026 Open access

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Authors: Lea Separovic, Suzana Sabaiduc, Yuping Zhan, Samantha E Kaweski, Sara Carazo, Romy Olsha, Richard Mather, Christine Lacroix, Maan Hasso, Inès Levade, Isabelle Meunier, Agatha N. Jassem
+4 more Katie Dover, Ruimin Gao, Nathalie Bastien, DM Skowronski
DOI: 10.1111/irv.70222
Cited by: 3
References: 25

Abstract

The Canadian Sentinel Practitioner Surveillance Network used the test-negative design to assess KP.2 vaccine effectiveness (VE) against medically attended outpatient COVID-19 between November 2024 and April 2025 among participants ≥ 12 years. Analyses included 5410 controls (19% vaccinated) and 435 COVID-19 cases (10% vaccinated). Nearly three-quarters (72%) of contributing case viruses were genetically characterized, with XEC (35%) and KP.3.1.1 (38%) variants most commonly identified. Vaccination reduced COVID-19 risk by approximately half (54%; 95% CI: 36-68) relative to unvaccinated individuals. VE was greatest during the first 2 months postvaccination, reducing risk by two-thirds and declining to minimal protection by the fifth month postvaccination.

Fields of Study & Subjects

SARS-CoV-2 and COVID-19 Research COVID-19 Clinical Research Studies Long-Term Effects of COVID-19

Publication details

Journal / source
Influenza and Other Respiratory Viruses
Publisher
Wiley
Volume
20
Issue
3
Pages
e70222–e70222
Publication date
1 March 2026
Language
EN