Flu cases are surging across the United States amid holiday travel, with New York state recording its highest weekly count of positive cases at 71,123 for the week ending December 20—a 38% increase over the previous week. The surge comes as a new flu strain, subclade K, a variation of influenza A(H3N2), drives outbreaks in Japan, the United Kingdom, and Canada. Fourteen states have reported high or very high activity of influenza-like illnesses.
Strain and Vaccination Trends
Health officials have been concerned that the current flu vaccine may not match the new variant, though they remain confident it provides protection against serious illness. Andrew Pekosz, co-director of the Johns Hopkins Center of Excellence in influenza research and response, noted that “cases are increasing, and we’re seeing a lot of influenza cases increasing across the country, and that’s a trend that we are sure will continue into the new year.”
Contributing to the surge is a decline in vaccinations. While more than 47.6 million flu vaccinations have been given at retail pharmacies and physician offices in the 2025-2026 season, this represents a decrease of about 3 million doses from the previous season. Jennifer Nuzzo, professor of epidemiology at Brown University, warned that “we’re potentially heading into a flu season that could be quite a doozy, and we know we’re starting it with fewer data and, more crucially, fewer vaccinations.”
Impact and Geographic Spread
The CDC estimates at least 4.6 million illnesses, 49,000 hospitalizations, and 1,900 deaths from flu so far this season. During the week ending December 13, two pediatric deaths were reported, bringing the total pediatric deaths to three. In Colorado, emergency department visits with a flu diagnosis increased 7% for the week ending December 20. In New York City, visits to hospital emergency rooms with a flu diagnosis rose to 8.75% for the week ending December 20, up from 6.76% the previous week.
States and territories with high or very high flu activity include Colorado, Connecticut, the District of Columbia, Georgia, Idaho, Louisiana, Maryland, Massachusetts, Michigan, New Hampshire, New Jersey, New Mexico, New York, North Carolina, Puerto Rico, and South Carolina. Symptoms of H3N2 include fever, cough, runny nose, fatigue, and muscle aches.
This article is an AI-assisted summary. All facts and figures are drawn from the original report: https://www.usatoday.com/story/news/health/2025/12/27/flu-cases-rising-new-york-colorado-louisiana/87927257007/