Overview
- CDC and state lab data this week show influenza activity rising earlier than normal, with clinical test positivity near 5% nationally and about 10.7% on the U.S. West Coast.
- Surveillance and lab analyses identify H1N1 as the dominant strain and report a new G155E mutation that early studies suggest some antibodies, especially from teens and young adults, do not recognize well.
- The 2026–27 vaccines approved in August target H1N1, H3N2 and one B strain and include newly available mRNA flu shots that manufacturers say can be made faster and may boost protection.
- Clinicians are urging vaccination for everyone six months and older now because protection takes about two weeks to develop, two vaccine components look well matched, and lower recent uptake could worsen pediatric and hospital burden.
- Flu shots typically cut hospitalizations and deaths by roughly 30%–60% depending on match and timing and offer peak protection about three to four months after vaccination, so public health officials stress early vaccination and prompt antiviral treatment for high-risk patients.