No.

A new influenza A(H3N2) virus strain renamed “H3N2 subclade K,” which is circulating widely today, was identified by health organizations months after the seasonal influenza vaccine was developed.
The World Health Organization selected the components for the northern hemisphere influenza vaccine between February and March of this year. Since August, there has been a rapid increase of A(H3N2) subclade K.
The Centers for Disease Control and Prevention explains that even if the current vaccine does not match the flu virus mutation that is currently being spread — the “K” variant — vaccination continues to protect against severe illness, hospitalization and death, as well as offering protection against other influenza viruses and help reduce the overall community spread.
Connecticut Public Health confirmed a Hartford County resident died from influenza the week of Oct. 25.
This fact brief is responsive to conversations such as this one.
CT Mirror partners with Gigafact to produce fact briefs — bite-sized fact checks of trending claims.
Sources
- Weekly US Influenza Surveillance Report: Key Updates for Week 48, ending November 29, 2025 Center for Disease and Control
- World Health Organization Seasonal influenza – Global situation
- World Health Organization Recommended composition of influenza virus vaccines for use in the 2025-2026 northern hemisphere influenza season
- Connecticut Department of Public Health Connecticut Department of Public Health announces first influenza death of the 2025-26 season
- Center for Disease and Control How Flu Viruses Can Change: "Drift" and "Shift"

