What question did this study set out to answer?

To evaluate the effectiveness of the KP.2 vaccine against outpatient COVID-19 in Canada.

March 7, 2026

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

Key Points

To evaluate the effectiveness of the KP.2 vaccine against outpatient COVID-19 in Canada.
Used a test-negative design for assessing vaccine effectiveness.
Included participants aged 12 years and older.
Analyzed data from 5410 controls and 435 COVID-19 cases.
Genetically characterized nearly 72% of contributing case viruses.
Vaccination reduced the risk of COVID-19 by approximately 54%.
Vaccine effectiveness was highest in the first two months post-vaccination, with a risk reduction of two-thirds.
Protection declined significantly by the fifth month post-vaccination.

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.

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Cite This Study

Separovic et al. (Sun,) studied this question.

synapsesocial.com/papers/69abc1535af8044f7a4e9def https://doi.org/https://doi.org/10.1111/irv.70222

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