Flu season in New York & New Jersey: The densest transit corridor in North America makes flu move fast
When flu arrives in New York City, it doesn't spread — it explodes. The NYC subway carries over 3 million riders on a typical weekday, NJ Transit moves another 300,000, and the commuter corridors extend flu's reach into every suburb within 60 miles. Regions with this kind of transit density see activity go from Very Low to High in three to four weeks. The rest of the country watches New York as a leading indicator — when Region 2 peaks early, a national wave usually follows within a month.
Current flu activity — HHS Region 2
This data is pulled live from the Delphi CMU Epidata API, which mirrors CDC FluView ILINet data for HHS Region 2. It reflects the most recent week available — typically data through the prior Saturday, published by the CDC the following Thursday.
States in HHS Region 2
HHS Region 2 covers New Jersey and New York. These states are grouped together by the Department of Health and Human Services for federal health program administration, and the CDC uses the same regional boundaries for flu surveillance reporting. ILI activity data is aggregated across all ILINet providers in the region, so the number reflects the regional average — individual states can vary significantly.
When flu typically peaks here
HHS Region 2 is consistently one of the earliest-peaking regions in H3N2-dominant years, with flu often reaching its high point in late December or the first two weeks of January. In H1N1-dominant or late-season years, the peak shifts to late January or early February, but Region 2 still tends to lead or match the national timeline rather than lag it.
The transit effect is measurable. Studies of NYC flu spread show activity can radiate from Manhattan outward along subway and commuter rail lines, reaching outer boroughs and New Jersey within days of a surge in Midtown. The Thanksgiving and Christmas travel spikes — Amtrak, airports, holiday crowding — act as additional accelerants each year.
Upstate New York runs a different pattern. Buffalo, Rochester, and Albany see activity roughly in line with the national average, without the December surge that hits the NYC metro. If you're in upstate NY, the Region 2 numbers can look alarming before you've personally noticed much flu around you.
What drives New York & New Jersey flu patterns
Mass transit density. No region in the country has a comparable combination of subway ridership, commuter rail, and inter-city transit. Flu researchers have documented that NYC's transit network is a primary driver of the city's early and rapid flu peaks. The effect is visible in contact-tracing data: transmission clusters map onto transit corridors.
Tourism and international travel. New York City is the country's top international tourism destination and a major entry point for new flu strains. In some years, strain variants that circulate in Europe or Asia before the US season starts arrive in NYC first, giving the city a head start on both spread and detection.
High-density housing. The five boroughs have the highest residential density in the US. Apartment buildings, shared hallways, and elevators are efficient transmission environments. Studies of NYC respiratory illness show building-level clustering during flu season.
New Jersey's commuter character. New Jersey's dense suburban-to-NYC commuter population means the state's flu patterns are largely driven by NYC spread. Bergen, Essex, and Hudson counties — the NYC-adjacent suburbs — typically show activity within a week of Manhattan's surge.
Recent seasons in HHS Region 2
Regional peak timing and severity can vary substantially from the national picture. The table below shows Region 2-specific peak months and severity for recent seasons, based on CDC FluView regional ILI data.
| Season | Regional peak | Dominant strain | Severity | Notable |
|---|---|---|---|---|
| 2024–25 | January | H3N2 / H1N1 | High | Above-average; NYC metro peaked early; NJ followed within a week |
| 2023–24 | December–January | H1N1 | Moderate | Moderate season; NYC showed early activity before national rise |
| 2022–23 | December | H3N2 | Very High | Severe; NYC one of earliest and highest-activity metros nationally |
| 2021–22 | February | H3N2 | High | Compressed post-COVID season; later peak than typical for Region 2 |
| 2019–20 | January | H1N1 | High | Strong season; ended abruptly March with COVID shutdowns |
When Region 2 crosses into High, the national peak is usually 3–5 weeks away. If you're in another part of the country and you see New York at High or Very High, that's your window to make sure you're vaccinated and have rapid tests at home. Check current activity nationwide. →
How to use this data
The live activity level above reflects the most recent week of CDC ILINet data for Region 2. There is always roughly a one-week lag between real-world conditions and published numbers — providers report weekly, the CDC publishes Thursdays, and this page reflects those numbers. During a rapidly rising season, treat the current level as a floor.
The ILI percentage is the share of outpatient visits attributed to influenza-like illness across all ILINet reporting providers in the region. It is not a case count and does not capture people who don't seek care. In regions with lower healthcare utilization rates (rural areas, communities with limited access), ILI percentages tend to understate true community activity.
For the most complete picture of the current season — including strain typing, lab positivity trends, and hospitalization data — the IsItFluSeasonYet homepage shows all of this in context. The regional activity shown here is the same data source as the homepage's region breakdown.