Flu Cases Spiking In NJ: What To Know About Subclade K

New Jersey is experiencing roughly double the number of flu cases it did last year, according to the state’s Department of Health (DOH).

On Dec. 27, the NJ DOH reported 12,211 cases of the flu. In December of 2024, roughly 5,796 flu cases were reported.

Experts say that these numbers are “nowhere near the total number of cases in the state," given that many flu cases go unreported.

Of the 12,211 cases reported this past December, almost 600 of them resulted in hospitalizations. More than half of the hospitalized patients were 65 years and older, state data indicates.

Flu-related deaths have also increased by fivefold last month, with 15 deaths reported by Dec. 27, 2025, compared to just three by Dec. 28, 2024.

While experts say predicting the flu season severity is nearly impossible, these elevated numbers come after the season had a late start. State data, along with health experts, say that it will get worse before it gets better.

"All indicators are showing that influenza activity remains elevated across New Jersey," said DOH spokesperson Dalya Ewais. "As of the week ending (Dec. 27), influenza-related emergency department visits resulting in hospital admissions and outpatient visits for influenza-like illness surpassed levels observed in previous weeks of the current season and exceeded peak activity reported during the past two influenza seasons."

One reason for the elevated number of flu cases this year may be because of a new strain, influenza A(H3N2) called subclade K, which is sweeping the globe.

"The type of flu that is circulating right now has mutations in it, which take it a little bit further away than the strains that have circulated in the past," NJ DOH Medical Director Ed Lifshitz previously told Patch. "People can not have as much immunity to it as they have in the past... There's some suggestion that it can cause a worse flu season than typical."

Although the current flu vaccine offers protection against the H3N2 strain, it doesn’t cover subclade K, which hadn’t been identified when the vaccine was developed. The variant has mutated seven times, making H3N2 an even more serious threat, according to experts.

Read More: New Flu Mutation Causes Severe Illness

Officials advise that it’s not too late to get the flu vaccine. While it may not prevent contracting the flu, it can reduce the severity of the symptoms, experts say.

Vaccination rates have been dwindling over the years. According to CDC data, around 40.3 percent of New Jersey children six months and older had received the flu vaccination by the end of November 2024, down roughly three percent from 2023. This year, just 38.1 percent of children got the jab by the end of November.

During the 2024-2025 flu season, 287 children died across the country, including five between the ages of 0 and 4 in New Jersey, according to state health data. No children have been reported to have died due to flu in New Jersey this season, but 43 pediatric cases have been labeled severe, as of Dec. 28.

Click here to find a flu vaccination clinic near you. The shot is recommended for people 6 months and older.

Cases of COVID and RSV have also seen a spike this season, according to state data.

Read More: NJ Flu Cases Triple As Vaccination Rates Go Down, Worrying Experts

What To Do If You Have The Flu

Most people who contract the flu typically get over it within a week or two with no long-lasting effects. Typical symptoms include fever or feeling feverish/chills, cough, sore throat, runny or stuffy nose, body aches, headaches, fatigue, and vomiting or diarrhea (more common in children).

Some patients may consult with a doctor to get medications like Tamiflu, or will combat symptoms with over-the-counter medications like Tylenol.

However, it’s important to know when flu symptoms prompt emergency medical care, according to the CDC. See the list of warning signs that require emergency care:

In Children:

• Fast breathing or trouble breathing
• Bluish lips or face
• Ribs pulling in with each breath
• Chest pain
• Severe muscle pain (child refuses to walk)
• Dehydration (no urine for 8 hours, dry mouth, no tears when crying)
• Not alert or interacting when awake
• Seizures
• Fever above 104 degrees Fahrenheit that is not controlled by fever-reducing medicine
• In children younger than 12 weeks, any fever
• Fever or cough that improves but then returns or worsens
• Worsening of chronic medical conditions

In Adults:

• Difficulty breathing or shortness of breath
• Persistent pain or pressure in the chest or abdomen
• Persistent dizziness, confusion, and inability to arouse
• Seizures
• Not urinating
• Severe muscle pain
• Severe weakness or unsteadiness
• Fever or cough that improves but then returns or worsens
• Worsening of chronic medical conditions