Antigenically drifted influenza A(H3N2) subclade K viruses have contributed substantially to influenza burden since 2025, but their clinical severity is less well described. Using sentinel surveillance data from Thailand, we found no significant difference in the adjusted odds of hospitalization among those infected with subclade K versus other influenza viruses (adjusted odds ratio 1.06, 95% confidence interval 0.67, 1.68). This approach to estimating hospitalization risk for an emerging influenza virus subclade using sentinel surveillance data could serve as a model for conducting future rapid assessments.