'Super Flu' Sickens NJ. How Effective Is The Vaccine?

Influenza is running rampant through New Jersey this winter, with the first pediatric flu death being reported last week. The latest variant, subclade K, has been dubbed the "super flu." Subclade K is a mutation of the H3N2 strain.

Between the week ending of Dec. 6, 2025, and the week ending Jan. 3, 2026, a total of 8,164 cases of the flu were reported in children between 0 and 4 years old, state data shows.

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

Dr. Ed Lifshitz, the Medical Director for the New Jersey Department of Health (NJDOH), says that the actual number of flu cases is more than this, given that many flu cases go unreported.

Health officials continue to recommend vaccination to defend against flu infection. Vaccines are updated each year to tackle the most common strains. While this year's flu shot doesn't cover subclade K as it wasn't identified when the vaccine was developed, health experts say that getting a flu shot is still the best way to prevent infection.

"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," 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."

Though a flu vaccine is typically recommended earlier in the season, officials say it is not too late to get one. While it isn't perfectly formulated against the current strain, it can still reduce symptoms and shorten the length of the infection, according to health experts.

"Flu typically causes symptoms such as mild fever and decreased appetite, but for some people, such as children and older adults, an influenza infection can become more severe and may even result in hospitalization," said Jennifer Turkish, MD, a primary care provider with Primary & Specialty Care at Old Bridge and a member of RWJBarnabas Health Medical Group. "Vaccination reduces these risks."

More people who get the flu are able to recover at home with rest, fluids and over-the-counter medications. If symptoms are severe or worsen, or if you are at high risk for complications, contact your health care provider.

People who are sick should seek emergency care right away if they have trouble breathing, constant chest pain, confusion, severe vomiting, or if they start to feel better but then get worse again with a higher fever or stronger cough. For children, get emergency care if their skin looks bluish, they are not drinking enough fluids, or they are very sleepy and hard to wake.

This article contains additional reporting by Jack Slocum.