Deep dive: Early flu season on the West Coast collides with measles resurgence — what parents should watch

This is a news briefing, not medical advice. Talk with your pediatrician about flu shots, MMR timing, and any symptoms.

Background

Flu seasons in the United States usually build from October and peak between December and February, often starting in the Southeast and moving west. The 2025–26 season closed with at least 198 pediatric flu deaths, a reminder of how hard the virus can hit young children.

Measles has also returned at scale. CDC reported 4,410 confirmed U.S. cases as of 15 October 2026—the highest total since 1991—driven largely by Pennsylvania and other low-vaccination communities. Infants under 12 months cannot receive routine MMR and depend on community immunity.

What changed this week

CDC FluView for the week ending 10 October 2026 shows seasonal influenza activity increasing but still low nationally. Multiple indicators have been rising since late August/early September. The clearest early signal is on the West Coast.

Seattle Children’s reported roughly 150 children testing positive for flu in a recent two-week stretch—levels the system typically sees only in early December. King County ER visits for influenza reached 233 in one September week versus 31 the year before. San Diego’s Rady Children’s has seen increased hospitalizations and ICU cases amid low vaccination rates so far this season. Alaska, Hawaii, and parts of California show the same early pattern.

Public-health laboratories report predominantly influenza A(H1N1)pdm09 this week. National percent positivity is still modest (around 3–4 percent), but regional numbers on the West are higher.

Competing viewpoints

Some clinicians describe the West Coast start as “about two months early” and urge immediate vaccination for everyone 6 months and older so protection is in place before wider spread. Others note that early activity does not automatically mean a more severe national season; flu remains unpredictable, and most of the country still shows minimal activity.

The measles context adds weight. Hospitals already managing a large measles outbreak may face overlapping respiratory pressure if flu continues to climb while RSV window protection is still rolling out. Parents in outbreak counties face dual decisions: keep well-child visits, ask about MMR timing for eligible children, and not delay the flu shot.

What to watch next

Sources: CDC FluView week 40 (ending 10 Oct 2026); Seattle Children’s and King County public-health reports; Rady Children’s San Diego notes; CDC measles dashboard (4,410 cases as of 15 Oct).