The influenza season has begun earlier than expected in New York City, with doctors reporting a sharp rise in cases weeks ahead of the usual timeline, raising concerns among public health officials and hospitals.

Data from the US Centers for Disease Control and Prevention (CDC) show that New York City, along with nearby regions such as Long Island and northern New Jersey, recorded some of the highest levels of flu-like illness in the country as of early December. City health authorities confirm that flu infections are increasing rapidly across the metropolitan area.

New York City’s acting health commissioner, Dr Michelle Morse, warned that flu cases are “skyrocketing” and urged residents to get vaccinated and take basic precautions, including staying home when unwell, wearing masks if symptomatic, and seeking medical care when necessary.

The growing outbreak has already disrupted daily life. Poly Prep Country Day School, a private school in Brooklyn, temporarily closed its Dyker Heights campus after nearly one-third of its middle and high school students fell ill over a span of just a few days. The closure allowed for an “intensive disinfection” of the facility before classes resumed, school officials said.

Health experts attribute the rapid spread in part to the dominant flu strain this season, H3N2, which appears to have undergone changes that may help it partially evade immune defences. While this could reduce the effectiveness of the flu vaccine compared with some previous seasons, early data from the United Kingdom suggest that vaccination still provides significant protection against severe illness and hospitalisation.

“It’s earlier and faster this year, and the trajectory is much quicker than usual,” Dr Bruce Farber, chief of public health and epidemiology at Northwell Health in Manhasset, New York, told The New York Times.

Emergency departments across the city are already feeling the strain. According to city health data, the proportion of emergency room patients diagnosed with influenza rose from 0.6 per cent to 1.6 per cent in a single week in late November, before climbing further to 3.4 per cent the following week.

Public health officials warn that this season could mirror last year’s severe outbreak. By the end of November, New York City had reported more than 10,000 laboratory-confirmed flu cases—a threshold that was not reached until late December during the previous flu season. Statewide, over 3,000 people have already been hospitalised with influenza, accounting for nearly 10 per cent of last season’s total hospitalisations.

Despite the surge, vaccination coverage remains low. Only about 22 per cent of residents outside New York City have received a flu shot so far this season. Within the city, just over 25 per cent of children aged six months and older are vaccinated, marking a 6.5 per cent decline compared with the same period last year.

Health authorities continue to stress that vaccination, along with early testing and responsible public behaviour, remains the most effective way to curb the spread and reduce the risk of severe flu-related complications.