CDC labels the 2025–26 U.S. flu season ‘moderately severe’ as estimated illnesses reach 11 million
U.S. health officials reported that influenza activity remained elevated as winter progressed and, for the first time this season, categorized 2025–26 as ‘moderately severe.’ CDC estimates cited millions of illnesses and substantial hospitalizations, with experts pointing to holiday travel and lower vaccination uptake as key drivers.
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Flu activity remains high as winter peaks
U.S. Centers for Disease Control and Prevention data indicated that seasonal influenza activity remained elevated heading into early January, and the agency classified the 2025–26 flu season as “moderately severe,” according to a Reuters report published on January 5, 2026. The report cited CDC estimates of at least 11 million illnesses, 120,000 hospitalizations, and 5,000 deaths so far this season. ([investing.com](https://www.investing.com/news/stock-market-news/us-cdc-says-202526-flu-season-moderately-severe-as-cases-hit-11-million-4430595?utm_source=openai))
That classification matters for health systems because it signals sustained burden, not just localized spikes. A moderately severe season can strain emergency departments and inpatient capacity, especially when influenza overlaps with other seasonal respiratory viruses and winter weather disruptions that delay routine care.
Drivers: travel, vaccination gaps, and misinformation
Public health experts cited in the Reuters report pointed to holiday travel, low vaccination rates, and misinformation as factors contributing to the surge in cases, and CDC indicated flu activity could continue for several weeks. ([investing.com](https://www.investing.com/news/stock-market-news/us-cdc-says-202526-flu-season-moderately-severe-as-cases-hit-11-million-4430595?utm_source=openai))
Holiday travel compresses exposure across regions, creating a mixing effect: people bring infections into communities with different baseline immunity and vaccination uptake. When vaccination is lower, the virus has more opportunity to spread, and the number of severe cases rises even if the virus itself is not more lethal.
Dominant strain and what it implies
The report said Influenza A(H3N2) remained the dominant strain among subtyped influenza A cases. Historically, H3N2-dominant seasons can be associated with higher impacts on older adults, though outcomes depend on population immunity and vaccine match in a given year. ([investing.com](https://www.investing.com/news/stock-market-news/us-cdc-says-202526-flu-season-moderately-severe-as-cases-hit-11-million-4430595?utm_source=openai))
For individuals and families, the practical takeaway is that prevention and early care decisions still matter late in the season: vaccination can reduce severe outcomes even after the season begins, and staying home when sick reduces downstream risk for high-vulnerability contacts.
What health systems and the public are watching
- Hospital and ICU capacity in regions with simultaneous winter weather disruptions.
- School absenteeism and workplace outbreaks that accelerate community spread.
- Updates from CDC as the season’s cumulative burden is revised over time.
Because CDC seasonal burden estimates are updated as surveillance data accumulates, the total impact can change over subsequent weeks—making continued monitoring important through the remainder of winter.