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

## TL;DR

The KP.2 vaccine was moderately effective against outpatient COVID-19 in Canada, with protection waning over time.

## Contribution

This study provides real-world evidence of KP.2 vaccine effectiveness against outpatient COVID-19 in Canada during late 2024 to early 2025.

## Key findings

- Vaccination reduced the risk of outpatient COVID-19 by approximately 54%.
- Protection was strongest in the first two months post-vaccination.
- Effectiveness declined significantly after five months.

## 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.