Flu Cases Climb Nationwide as Holiday Travel Spurs Spread, CDC Reports

Influenza activity is intensifying across the United States as millions of people travel and gather for year-end celebrations, according to the latest surveillance figures from the Centers for Disease Control and Prevention (CDC). Data updated through December 19 indicate that the 2025-26 season has already generated an estimated 4.6 million symptomatic illnesses, 49,000 hospitalizations and 1,900 deaths. Epidemiologists anticipate further increases through January, a period that historically sees peak transmission.

Dominance of a New H3N2 Subclade

Genetic analysis performed by the CDC shows that a recently identified branch of the H3N2 virus is driving much of this season’s activity. Among 163 H3N2 samples collected since September 28 and sequenced in federal laboratories, 89 percent belonged to “subclade K,” a lineage that first gained traction during the Northern Hemisphere summer in several countries. H3N2 is one of two major subtypes of influenza A and is frequently associated with higher rates of severe outcomes in older adults.

Pediatric Impact Remains a Concern

Although adults account for most hospital admissions, influenza continues to pose a serious threat to children. An ABC News review has identified three pediatric deaths linked to flu since the season began. Last season, the United States recorded 288 influenza-related pediatric fatalities, matching totals seen during the 2009 H1N1 pandemic. A CDC study released earlier this year found that roughly 90 percent of the children who died in 2024-25 had not received a flu vaccine.

Record-High Weekly Cases in New York State

New York is currently experiencing its most intense weekly surge since state-level reporting became mandatory in 2004. The New York State Department of Health (NYSDOH) documented 71,123 laboratory-confirmed cases for the week ending December 20, representing a 38 percent jump from the prior week’s 51,365 infections. Cumulative reports now total 189,312 cases statewide.

Hospital burden is rising in tandem. NYSDOH figures show that weekly influenza-related admissions increased by 63 percent, moving from 2,251 to 3,666 hospitalizations over the same seven-day period. Emergency departments across the state have reported heavier patient volumes, mirroring national trends.

Preventive Measures and Vaccination Guidance

Public health agencies are urging residents to adopt layered prevention strategies while influenza remains widespread. These steps include wearing well-fitting masks in crowded indoor spaces, washing hands frequently with soap and water, and staying home when symptomatic. The CDC continues to recommend that everyone aged six months and older, barring rare medical contraindications, receive an annual flu shot. The agency estimates that seasonal vaccination prevents millions of illnesses and doctor visits each year and significantly reduces the risk of severe complications.

Individuals who develop fever, cough, sore throat or other flu-like symptoms are advised to seek medical guidance promptly, particularly if they fall into a high-risk category such as young children, adults over 65, pregnant people or those with chronic conditions. Antiviral medications are most effective when initiated within 48 hours of symptom onset.

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Ongoing Surveillance and Outlook

Influenza transmission typically accelerates during late December and early January, coinciding with increased travel and indoor social activities. Public health officials monitor outpatient visits, laboratory confirmations, hospitalizations and mortality to gauge severity and allocate resources. Weekly flu tracking updates are published on the CDC’s official influenza surveillance portal, providing national and regional snapshots of viral activity.

While emergency departments are recording more flu-related visits, clinicians report that the clinical presentation to date is consistent with prior seasons, and there is no indication that the circulating strains cause unusually severe disease. The principal concern is the sheer number of infections occurring in a compressed timeframe, which can strain hospital capacity and disrupt workplaces and schools.

Experts emphasize that community mitigation efforts undertaken now can reduce the trajectory of hospitalizations in the coming weeks. Vaccination remains the cornerstone of that strategy, supplemented by personal hygiene and prompt treatment of confirmed cases. With several weeks of elevated transmission expected, health authorities continue to highlight the importance of vigilance as the holiday period concludes and routine activities resume in the new year.

Crédito da imagem: Natalia Lebedinskaia/Stock Photo/Getty Images