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The 'Superflu', Not Super Great?

  • Writer: Blue Gold Wizard
    Blue Gold Wizard
  • Jan 29
  • 3 min read

By VALENTINA CORTEZ.



Prepare for a new flu vaccine. One that is more effective, offering more immunity because there’s a flu strain emerging. The newly influenza A strain, H3N2 subclade K. 


The new strain, subclade K, was first detected in Australia in July 2025, and then later found in Japan and the United Kingdom, giving a start to an unusually early flu season. After scientists spotted this new variant, they noticed it expanding rapidly during the southern hemisphere’s flu season, and in several northern hemisphere countries. 


Influenza activity was low before Thanksgiving 2025, but has since risen following holiday travel and school reopening, with the Centers for Disease Control and Prevention (CDC) reporting at least 2.9 million illnesses, 30,000 hospitalizations, and 1,200 deaths during the 2025-2026 season. Most cases were reported to be a result of the influenza A (H3N2), with the K subclade now predominating. 


Mr. Saltz, one of the nurses at Washingtonville Senior High School, recalls a high count of students with fevers that were sent home since Thanksgiving. “We saw more kids that we’ve never met before over the last few months than any other time I can remember. If someone comes to the nurse and they ask you, is this the nurse’s office? They’ve never been here before, and if they’re not feeling well, something’s not right.” 


Every age group remains at risk, but a high number of children have been hospitalized for the flu. As of Jan. 9, the U.S. had seen 17 deaths of children due to the flu this season. Since the new strain appeared, there has been prolonged fever. Children are arriving in the emergency room after having a high fever of more than 104 degrees for 5-7 days, or with flu complications including febrile seizures, croup, or severe dehydration. 


While the CDC stated that there’s currently no evidence to support that this specific variant causes more severe illness on an individual level compared to other H3N2 strains, its ability to spread rapidly means a higher total volume of severe cases. First, there was a sharp uptick in flu cases in mid-December 2025. Later, in early January, New York state recorded the highest number of flu cases in a single week. Currently, 44 out of the 55 states and other jurisdictions are reporting high or very high flu activity. 


The ‘Superflu’ is not a scientific term, and there’s no indication that subclade K is any more dangerous than other H3N2 influenced viruses. “This is the same subtype we have had circulating in the human population since 1968. But each season, the virus evolves to evade immunity, and some seasons it’s relatively more successful than others,” explains Danuta Skowronski, MD, the epidemiology lead for influenza and emerging respiratory pathogens at the British Columbia Centre for Disease Control, to CIDRAP News. 


It’s important to note that the strains that were chosen to be included in the 2025-2026 flu vaccine weren’t a great match for the predominantly circulating subclade K. 


Regardless of the variant’s unknown intensity, vaccination remains encouraged. Mrs. Davy, one of the nurses at Taft Elementary School in Washingtonville, shares her experience that stimulated vaccination. “When I was a new nurse, working at Sloane, I started to not feel well. Within hours, I went from being fine to being sick. The following year, I was a travel nurse in Vail, Colorado. They offered me the vaccine, and I took it. I really couldn’t move for a week [without it]. Now, I always get the flu shot.” Getting vaccinated for the flu has proven to decrease the risk of serious illness, hospitalization, and death. Vaccinated people appear to generate good antibody responses against currently circulating influenza viruses, including subclade K. Waiting longer to be vaccinated limits the window in which the vaccine is most effective. It takes a couple of weeks for the flu shot to transmit its maximal benefits. 


Although the mutations in the strain, H3N2 subclade K, are not associated with increased severity, it’s best to be vaccinated and educated about the strain’s ability to evade some immunity, in case it results in more flu cases.


 
 
 

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