If it appears like everybody round you has come down with the flu, you are not imagining it.
As of Jan. 9, the U.S. Facilities for Illness Management and Prevention (CDC) estimates that a minimum of 15 million folks have gotten sick with the flu this season. Of these, 180,000 have been hospitalized, and seven,400 folks have died from flu thus far, together with 17 youngsters.
At Phoenix Kids’s Hospital, flu circumstances have been excessive since mid-December 2025, stated pediatric infectious illness specialist Dr. Monica Abdelnour.
“Though the CDC [currently] estimates this flu season to be of reasonable severity, the charges we’re seeing are much like, and in some circumstances barely greater than, these noticed within the 2024-2025 season, which was deemed high-severity,” she instructed Stay Science in an e mail. “It stays potential this flu season could in the end be categorized as excessive severity as effectively.”
Whereas the CDC reported a slight dip within the variety of lab-confirmed flu circumstances within the first week of 2026, in comparison with the final week of 2025, Madad instructed Stay Science that it is “too early to declare we’re previous the height.” Flu exercise within the U.S. normally peaks someday between December and February. The CDC additionally famous that the small drop in confirmed circumstances could possibly be linked to anticipated decreases in physician visits and testing through the holidays, not an precise drop in flu unfold.
What’s subclade Ok?
A whole lot of the discuss this yr’s flu season has centered on one thing referred to as “subclade Ok.”
To know what that is, it is vital to know that flu viruses are always evolving, gaining small genetic mutations as they unfold. Scientists maintain monitor of how flu viruses change utilizing a system much like a household tree, Madad stated.
The large branches of this tree are referred to as “sorts.” This contains influenza A and B, that are broad teams of flu viruses. These massive branches sprout off into smaller branches referred to as subtypes, equivalent to A(H3N2) or B/Victoria lineage.
The letters H and N, that are used to distinguish influenza A subtypes, stand for 2 proteins on the virus’s floor: hemagglutinin (H) and neuraminidase (N). There are lots of potential variations of every protein — 18 and 11 variations, respectively — which consequently offers rise to a big number of flu viruses, of which only some routinely infect people.
Going even additional down a department, scientists establish “clades,” that are teams of viruses that got here from a standard ancestor and share related genetic traits. A subclade is an excellent smaller group inside a clade — a more recent “twig” on the tree — that shares current mutations.
This flu season, the CDC reported that most flu circumstances are being brought on by the influenza subtype A(H3N2). Of the greater than 430 samples of influenza A(H3N2) virus collected since late September 2025, over 91% have been recognized as a part of a intently associated group referred to as subclade Ok.
Is subclade Ok a “tremendous flu”?
The reply isn’t any.
Subclade Ok carries distinct mutations in elements of the virus that our immune techniques normally acknowledge, Madad stated. Due to this, our immunity from previous flu infections or vaccinations is decrease than it is perhaps if the subclade appeared extra “acquainted.” This allows the virus to unfold extra simply, leading to extra circumstances and, in consequence, extra hospitalizations.
Nonetheless, that doesn’t robotically imply subclade Ok is extra lethal or causes extra extreme sickness than different circulating flu viruses, Madad stated. Present epidemiologic knowledge present that subclade Ok doesn’t result in extra extreme illness than different seasonal flu strains than are spreading now, she famous.
“Flu signs this yr are much like these seen in earlier seasons,” Abdelnour added.
Folks with the flu generally expertise fever or chills, cough, nasal congestion, muscle and/or physique aches, complications and fatigue. In extreme circumstances, flu infections can result in problems equivalent to sepsis and pneumonia. Adults 65 and up; younger youngsters, particularly these below 2; pregnant folks; and other people with power circumstances like bronchial asthma, diabetes or coronary heart illness are at highest danger for extreme flu problems.
Is that this yr’s flu vaccine working, and is it too late to get it?
The flu vaccine “could also be a much less excellent match for subclade Ok” than it could possibly be, Madad stated, however she harassed that vaccination nonetheless performs a important function in stopping critical sickness. Abdelnour stated that the annual flu vaccine reduces the danger of significant problems, equivalent to sepsis, pneumonia and vital neurologic signs, equivalent to seizures.
Knowledge from the Southern Hemisphere, which experiences flu season earlier than the Northern Hemisphere, means that this yr’s flu vaccine works simply in addition to previous vaccines at reducing the danger of being hospitalized with the flu, Abdelnour stated. This previous flu season, the flu vaccine lowered flu-related physician visits and hospitalizations by 50% within the Southern Hemisphere, in keeping with a CDC report revealed in September 2025.
“That is throughout the typical vary, and it is anticipated we must always expertise related ranges of safety in america,” Abdelnour stated.
Sadly, fewer persons are getting vaccinated towards the flu this yr, and that is very true of youngsters, Madad stated. “Solely about 42% of U.S. youngsters have obtained the flu vaccine thus far this season, down from roughly 53% on the identical level in 2019–2020.” As of Jan. 3, about 44.1% of adults reported having obtained a flu vaccination.
Poor vaccination charges can have actual penalties, Madad stated. Throughout the 2024-2025 flu season, 280 youngsters within the U.S. died of flu-related sickness, and of these, about 9 in 10 had not been vaccinated towards the virus. Madad, who can also be a mom of 4, famous that each one of her youngsters obtain the flu shot yearly.
Though flu season began within the fall, “it isn’t too late to get the flu shot,” Abdelnour emphasised. “Given the present surge in circumstances, getting vaccinated now’s strongly advisable to guard your self and people round you.”
Madad echoed that recommendation, urging anybody who hasn’t but obtained a flu shot this season to take action, particularly adults ages 65 and older, pregnant folks, these with weakened immune techniques, and other people dwelling with power well being circumstances, who’re at greater danger of extreme circumstances.
How else are you able to shield your self from flu?
Vaccination is only one layer of safety. Madad emphasised sporting a well-fitting masks in crowded indoor areas and enhancing air flow for indoor gatherings. Moreover, folks ought to keep dwelling when sick to keep away from the danger of spreading flu to others. These steps assist restrict the unfold not solely of flu, however of different respiratory viruses like COVID-19 and RSV (respiratory syncytial virus), as effectively.
Abdelnour additionally famous the significance of practising correct hand hygiene. “Particular consideration must be given to childcare environments equivalent to colleges and daycare facilities,” she stated. “This contains recommending youngsters get their flu shot, encouraging handwashing with cleaning soap and water for a minimum of 20 seconds and maintaining youngsters dwelling when they’re sick to forestall the unfold of an infection to others.”
Are there remedies for flu?
For individuals who do get sick, antiviral medicines equivalent to Tamiflu may also help. These pharmaceuticals can scale back the severity of signs and shorten the time you’re sick, particularly when taken throughout the first day or two after signs start. Proof suggests they are often particularly useful to folks hospitalized for flu.
The CDC recommends immediate therapy for folks with suspected flu signs who’re at elevated danger of significant flu problems, together with pregnant girls and other people with power well being circumstances, equivalent to bronchial asthma, lung illness, diabetes, or coronary heart illness.
Madad stated that flu antivirals are “underused” and reminds folks at excessive danger of extreme flu or who’re caring for somebody who’s excessive danger to ask their medical doctors about antivirals shortly after they believe an an infection. The excellent news is that present knowledge present subclade Ok continues to be aware of the usual antiviral medicines medical doctors use for influenza, she stated.
This text is for informational functions solely and isn’t meant to supply medical recommendation.
