Early flu season sets October hospital high since 2010

The United States is in an early flu season that has already produced the highest mid-October hospitalisation rate in more than a decade, according to the Centers for Disease Control and Prevention. In its FluView report for week 41, published on 23 October and covering the week ending 17 October 2026, the CDC said the estimated weekly hospitalisation rate was the highest for that week since the 2010-2011 season.

Seasonal activity remains low nationally, the CDC said, but multiple indicators have been rising since late August or early September. That combination is what makes the timing notable: the virus is moving earlier than usual, before many people have had a flu vaccination for the current season, and hospital data are already showing a clear upward trend. Related health coverage on this site includes a recent report on brain disease among former professional football players.

The hospitalisation finding comes from FluSurv-NET, a population-based surveillance network that tracks laboratory-confirmed flu hospitalisations in selected counties in 14 states. The network represents approximately 10 percent of the population of the United States, so its rates are a sample-based measure rather than a count of every hospitalisation in the country.

FluSurv-NET counted 798 laboratory-confirmed flu hospitalisations in the period covered by the report. The observed weekly rate was 1.1 per one hundred thousand people, unchanged from the previous week. After accounting for reporting delays, the CDC estimated that the weekly rate likely ranged from 1.5 to 2.0, and the cumulative observed rate for the season so far was 2.1. The CDC report presents those figures as preliminary, with earlier counts updated as more reports arrive.

Age made a clear difference in the hospitalisation data. The highest observed rate was among adults 65 and older, at 7.4, followed by adults 50 to 64, at 2.3, and children 0 to 4, at 1.7. Those patterns are consistent with flu hitting older adults hardest in hospital terms, while also reaching young children at a higher rate than other younger age groups.

H1N1 is driving the rise

Clinical laboratories reported that 5.7 percent of specimens tested for flu were positive during the reporting week, up from the previous week. Public health laboratories subtyped 241 influenza A viruses during that week, and 239 of them were H1N1, or 99.2 percent of those subtyped. None of the subtyped viruses were H3N2, according to the CDC.

H1N1 in this report refers to influenza A(H1N1)pdm09, a virus that emerged in 2009 and has caused seasonal epidemics around the world since then. The CDC said most of the current H1N1 viruses belong to a genetic subgroup called D.3.1.1, which is dividing into groups showing different genetic changes. It is too early to know which viruses may predominate later in the season, or whether those changes will affect how well this season's vaccine works.

Laboratory testing offered some reassurance on vaccines. The CDC reported that 93.2 percent of recent H1N1 viruses tested were well recognised by antibodies raised against this season's vaccine strain. Formal estimates of vaccine effectiveness for this season are not yet available, the agency said. Annual flu vaccination is recommended for persons 6 months and older, and for most people it should ideally be offered during September or October, because vaccination in July or August is not recommended for most groups due to waning immunity over the season.

What other indicators show

Outpatient and emergency department data tell a calmer story than the hospitalisation rate alone. Visits for influenza-like illness, defined as fever plus cough or sore throat, accounted for 2.2 percent of outpatient visits reported through the national network, below the national baseline of 2.9 percent. Emergency department visits with a flu discharge diagnosis accounted for 0.9 percent of visits, stable compared with the previous week, although visits rose among young children and school-age children.

Hospitals reporting to a separate national system, the National Healthcare Safety Network, reported 4,811 laboratory-confirmed flu admissions during the reporting week. The admission rate was 1.4, stable compared with the previous week but trending upward, according to the CDC. Admission rates rose in several regions during the week, while remaining stable elsewhere. Coverage by Becker's Hospital Review noted the same mid-October comparison with the 2010-2011 season.

Mortality data remained limited. Deaths due to influenza accounted for 0.2 percent of deaths that occurred during the reporting week, stable compared with the previous week, according to national mortality surveillance data available to the CDC. No influenza-associated pediatric deaths occurring during the current season had been reported to the CDC at the time of the report.

A separate finding in the same report should not be confused with seasonal flu. A confirmed human infection with avian influenza A(H5N1) was reported during the reporting week, in a dairy cattle farm worker in Washington who developed eye irritation and upper respiratory symptoms. No human-to-human transmission of H5 viruses has been identified in the United States, the CDC said, and that case is distinct from the seasonal H1N1 activity described above.

For people who do become ill, the CDC notes that prescription flu antiviral drugs can treat flu illness and should be started as early as possible, especially for patients at higher risk of complications. Vaccination remains the agency's main preventive recommendation for the season, and the early rise in activity means the window for getting vaccinated before winter peaks is already narrowing. More health stories are collected on the site's Health topic page.