Flu Activity Is Low, but Next Season's Vaccine Got a Full Reset
Seasonal flu activity was low in the U.S. in the week ending Sept. 26, 2026. That is the headline from the CDC Weekly U.S. Influenza Surveillance Report for Week 38, published Oct. 2, 2026. CDC Week 38 Report
The CDC FluView U.S. Map for that same week listed activity as Minimal Activity. Week 38 was defined as ending Sept. 26, 2026. CDC FluView Map
FluView is the CDC weekly flu tracking report, prepared by the Influenza Division. The agency says all FluView data are preliminary and can be revised. The current index lists reports in order: Key Updates for Week 33 ending Aug. 22, Week 34 ending Aug. 29, Week 35 ending Sept. 5, Week 36 ending Sept. 12, and Week 37 ending Sept. 19, 2026.
The quiet late-September reading follows a 2025-2026 season that ran above normal through winter. The CDC set the national baseline at 3.1% for 2025-2026. Baseline is the threshold used to judge whether doctor visits for flu-like illness are normal or high. For Week 7 ending Feb. 21, 2026, visits were 4.4% with a stable trend. By Week 10 ending March 14, 2026, visits were 3.3% with a decreasing trend. CDC Week 7 Report
Earlier in that season, activity was high. CDC data showed seasonal flu activity stayed high and rose in the final week of December. In early January 2026, the CDC described the 2025-26 season as "moderately severe," with cases at 11 million. Reuters
The toll was large. The CDC Week 3 2026 report counted 11,000 deaths from flu so far that season. Separately, the CDC reported one child flu death in the prior week. That brought the 2025-26 total for children to nine as of early January 2026.
Attention has now shifted to the 2026-2027 recipe. The CDC 2026-2027 Flu Season page was dated Sept. 29, 2026. All three virus components in 2026-2027 U.S. seasonal flu vaccines were updated from the 2025-2026 vaccines.
For 2026-2027, the committee recommended U.S. egg-based vaccines contain an A/Missouri/11/2025 (H1N1)pdm09-like virus and an A/Darwin/1454/2025 virus. By comparison, the CDC lists the 2025-2026 vaccines as including an A/Victoria/4897/2022 (H1N1)pdm09-like virus and an A/Croatia/10136RV/2023 (H3N2)-like virus. The CDC says flu vaccines are available for people age 6 months and older during the 2026-2027 season.
Timing and dosing guidance is steady. The CDC says most people who need only one dose should ideally be vaccinated in September or October. For 2025-2026, the CDC recommended only single-dose formulations for children, pregnant women, and adults. The CDC says Fluzone High-Dose is an inactivated flu vaccine with four times the antigen, the ingredient that trains the immune system.
On process, FDA advisers recommended flu strains for the 2027 Southern Hemisphere season on Oct. 1, 2026. For the 2025-2026 U.S. season, the FDA selected strains without an advisory committee vote. Reuters
In my view, specialists will focus on the pairing here. Low levels between seasons are normal. Updating all three vaccine components is less routine. It resets how closely the shot matches circulating viruses, and it puts the September-October window in focus while activity is still minimal.
