STATEN ISLAND, N.Y. — A new flu strain has engulfed the United States, causing the highest flu infection rate in 25 years as New York City’s flu-related hospitalizations continue to rise at alarming rates, data shows.
Dubbed “super flu,” the strain, called A/H3, is responsible for 95% of cases in New York, according to the state Department of Health’s most recent data.
The strain is somewhat resistant to this year’s vaccine, which was created months before the outbreak, medical experts have reported. And since vaccination rates are down in the United States, more people are vulnerable to catching and spreading the virus, according to the U.S. Centers for Disease Control and Prevention.
The flu, a very contagious respiratory illness, is caused by influenza viruses that infect the nose, throat, and sometimes the lungs, according to the CDC.
Though it can be mild at times, it can also lead to severe illness, even death in children and vulnerable populations. Two pediatric deaths have so far been reported in New York City.
There were 130 hospitalizations on Staten Island for the week ending Dec. 27, 2025, an increase from the previous week, though the 1,297 cases reported on Staten Island for that week were a drop from the 2,429 reported the week prior, according to data. That’s still more cases than were recorded any single week in the last two flu seasons, the state Health Department said.
The contradiction may be caused by a time delay between infection and serious illness. Hospitalization numbers this week may reflect illness reported in a previous week, doctors said.
Also, many with mild symptoms don’t get tested at all, and may develop into serious symptoms, ultimately leading to hospital admission, local medical experts said.
“Children oftentimes are admitted due to dehydration and require IV fluids as part of their symptomatic care,’’ Dr. Dolly Sharma, a pediatrician at Northwell Staten Island University Hospital, Ocean Breeze, told the Advance/SILive.com. ”Recent holidays may have also been a factor, as families travel outside of town … may have still been experiencing mild symptoms but not sought medical attention or been tested.”
And several weeks of peak flu season lie before us, doctors said.
Influenza A activity in country usually peaks from January through March, Sharma said. Influenza B infection comes typically after Influenza A and it peaks from March through May, she said.
Most admissions for viral illnesses in the first three weeks of December were children with Influenza A, said Dr. Ana Mendez, chief of Ambulatory Pediatrics at Richmond University Medical Center in West Brighton. The same is true at RUMC’s Pediatric Clinic, she said.
Symptoms of ‘super flu’ variant
Doctors reported that this year’s most common flu variant presents similarly to last year’s variant, causing mild to severe illness, with one exception. Many patients have described vomiting “yellow bile” as one of the standout symptoms of their flu infection, according to a report on Healthandme.com. Virologists said they believe this may happen because the flu is suppressing appetite more than usual, leading people to vomit when their stomachs are empty.
Vomiting and diarrhea are more common in children than adults, the CDC reported.
Most common symptoms of the circulating variant include:
- Cough
- Sore throat
- Runny or stuffy nose
- Muscle or body aches
- Headache
- Fatigue
The flu is more dangerous for the pediatric population, as children can experience more GI symptoms, like vomiting and diarrhea, which can lead to dehydration, Sharma said, noting that some children may present with a bacterial pneumonia compounded with the flu virus, which can cause breathing difficulty.
“Severe complications occur in 6% to 20% of hospitalized children, including pneumonia as well as other bacterial co-infections, ICU admission and mechanical ventilation,’’ Sharma said. Neurologic complications occur in approximately 8% to 11% of hospitalized children, with influenza, mostly in kids 2 to 4 years of age, she said.
The CDC recommended flu antiviral treatment as soon as possible in people who are very sick or people at higher risk of developing serious complications because of their age or the presence of certain underlying conditions.
Vaccination is a critical element in prevention, Sharma said, echoing the advice of the CDC.