A new and aggressive form of the flu is spreading across the United States this season. This variant, known as subclade K of the influenza A H3N2 virus, is driving a notable increase in global flu cases, including within the U.S.
The World Health Organization has indicated that the emergence of this K variant signifies a significant evolution in H3N2 viruses, which has raised concerns about the effectiveness of the current influenza vaccine against this strain. Experts warn that subclade K leads to more severe flu symptoms, including fever, chills, headache, fatigue, cough, sore throat, and runny nose.
Recent data from the Centers for Disease Control and Prevention (CDC) reveals that out of 216 influenza A(H3N2) viruses collected since September 28, 89.8% belonged to this concerning subclade. The CDC continues to monitor flu activity weekly, tracking states that are experiencing increased outpatient visits for respiratory illnesses.
As of the week ending December 13, certain states are showing heightened levels of flu activity. New York City is categorized at a “very high” level of medical visits, with New York State and New Jersey also reporting severe activity. Meanwhile, other states such as Rhode Island, Louisiana, and Colorado are classified as having high activity levels.
The CDC estimates that the current flu season has already seen at least 4.6 million reported illnesses, 49,000 hospitalizations, and around 1,900 flu-related deaths. Although it remains unclear whether this year’s flu vaccine targets the K variant directly, public health officials strongly recommend vaccination as the most effective defense against the virus.
Dr. Neil Maniar, a professor of public health at Northeastern University, highlighted the severity of this new flu strain. He noted that past occurrences of this variant in other regions have led to significant illness, and the current season is already shaping up to be aggressive. With lowering vaccination rates, there are fears that the combination of a more virulent variant and diminished immunity among the population could exacerbate the situation.
Despite concerns about the vaccine’s alignment with the K variant, Maniar emphasized the importance of vaccination, stating it can still offer protection against serious illness caused by the strain. He reassured individuals that it is not too late to get vaccinated, especially as the peak of flu season approaches. He recommended vaccination for almost everyone, as even healthy individuals are at risk of severe illness from the flu.
Individuals typically begin to develop some immunity within a few days of vaccination, with full benefits seen in about two weeks, making it essential to get the vaccine soon. With many indoor gatherings expected in the coming months, protecting oneself and others becomes increasingly important.