New York City endured one of its harshest flu seasons on record in 2025–2026, with the Health Department reporting more than 32,000 positive flu cases in a single week in late December — the most the city has seen in one week since 2005 — and a season total that climbed past 146,000 cases by mid-February.

The data, released in a series of respiratory-virus updates from the Department of Health and Mental Hygiene, captured a season that hit children hardest and strained emergency rooms through the holidays. The week ending Dec. 20, 2025, marked the peak: more than 32,000 lab-confirmed cases, the highest single-week count since 2005, when the city began compiling full-year data.

A season that fell on children

More than half of this season’s flu cases — about 52% — occurred in children under 18, the department said. For the first time this respiratory virus season, the city also reported four pediatric flu deaths, a sobering marker in a year defined by high transmission. Pediatric flu deaths are individually rare and reportable, and each underscores the severity of a season that filled pediatric emergency departments through December and January.

The statewide picture matched the city’s. The New York State Department of Health reported its highest number of flu hospitalizations in a single week and, separately, the most flu cases ever recorded in one week, as the late-December surge swept the state. Influenza hospitalizations statewide jumped sharply during the peak.

RSV elevated, COVID low

The flu wasn’t the only virus circulating, but it dominated. RSV — respiratory syncytial virus — kept emergency-room visits and hospital admissions elevated, particularly among the youngest children, ages 0 to 4, for whom RSV can be most dangerous. COVID-19 activity, by contrast, stayed relatively low and stable through the season, with emergency-room visits and hospitalizations carrying a COVID diagnosis hovering at a fraction of a percent.

By mid-February, the worst appeared to be passing. The proportion of emergency-room visits and hospitalizations with a flu diagnosis had fallen to less than 0.5%, down from the December peak. But the season produced a late wiggle: lab-reported cases ticked up for the week ending Feb. 7 — the first increase since the week ending Dec. 20 — a reminder that flu activity can rebound.

”Flu season isn’t over”

Dr. Michelle Morse, the department’s Acting Commissioner and Chief Medical Officer, used the February uptick to renew the city’s vaccination message. “Although the uptick in flu cases this week has been small, it serves as a good reminder for all New Yorkers that flu season isn’t over,” she said, urging residents to get vaccinated if they had not already.

The department’s standing guidance is that everyone 6 months and older should get the season’s flu and updated COVID-19 vaccines. It recommends an RSV vaccine for adults 75 and older, and for those 50 to 74 with certain chronic conditions or other risk factors who have not previously received one.

A test for a strained system

The season landed as the city’s hospital systems were already navigating tight budgets and the early days of a new mayoral administration under Zohran Mamdani, who took office Jan. 1, 2026. High-volume respiratory seasons fall heavily on NYC Health + Hospitals, the public system that serves as a safety net for many New Yorkers without other options. A flu season that set a 20-year single-week record offered an early stress test of that system’s surge capacity — and a data-backed argument for the vaccination campaign the department has pressed all winter.

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Frequently Asked Questions

How bad was NYC's 2025–2026 flu season?
Severe. For the week ending Dec. 20, 2025, the Health Department logged more than 32,000 positive flu cases — the most in a single week since 2005, when full-year data first became available. The season total passed 146,000 cases by mid-February 2026.
How many children were affected?
More than half — about 52% — of this season's flu cases occurred in children under 18. The city reported four pediatric flu deaths this season.
What about RSV and COVID?
RSV emergency-room visits and hospital admissions stayed elevated, especially among children ages 0–4. COVID-19 activity remained relatively low and stable through the season.
Who leads the NYC Health Department?
Dr. Michelle Morse served as Acting Commissioner and Chief Medical Officer of the NYC Department of Health and Mental Hygiene during the season.