New K Variant Flu Outbreak: Rapid Spread, Fever, and Rising Risk of Lung Damage Explained

Cases of the flu are rising rapidly across the United States, driven by a new variant of the virus, gripping more than half of the states, even as holiday travel plays out. That variant, known as subclade

K, has led to early outbreaks in the UK, Japan, and Canada. Last week, the Centers for Disease Control and Prevention reported high or very high levels of illness among people, mostly youngsters. According to the CDC, there have been at least 7.5 million illnesses in the US, 81,000 hospitalisations, and 3,100 deaths from flu so far this season. That includes at least eight child deaths and is based on data as of Dec. 20, before major holiday gatherings. Doctors say the K variant of the strain is associated with common flu symptoms, which include fever, and carries a rising risk of complications like lung damage or pneumonia, especially in vulnerable populations. However, it is still not too late to get a flu shot, which, according to the doctors, can still prevent severe illness even if someone gets infected. While this year’s vaccine is not a perfect match to the subclade K strain, a preliminary analysis from the UK found it offered at least partial protection, lowering people’s risk of hospitalisation. The CDC says only about 42 per cent of adults and children have gotten a flu vaccination so far this year.

What is subclade K flu?

Subclade K is a newly emerged subgroup of a well-established human seasonal flu virus known as the H3N2 influenza A virus, which has circulated for decades. The variant was first spotted in June, and it was then noticed that it was expanding rapidly during the Southern Hemisphere’s flu season and in several Northern Hemisphere countries. Scientists believe the subclade K virus is a shape-shifter, constantly mutating, and it comes in multiple forms. There are two subtypes of type A flu, and subclade K is a mutated version of one of them, named H3N2. That H3N2 strain is always harsh, especially for older adults. Subclade K’s mutations are not enough of a change to be considered an entirely new kind of flu. But they are different enough to evade some of the protection from this year’s vaccine.

Does subclade K make people sicker?

While the CDC says it is too soon to know how severe this season will be, the variant can lead to serious illness. Doctors say it causes extremely high fever, along with signs of a cold and flu. In the long run, it can totally damage your lungs as well.

Flu season began early this year

Subclade K – which has spread to most parts of Europe as well – was first detected in Norway, followed by the UK, where the influenza season started 4 to 5 weeks earlier than usual. Lewis Japan also witnessed an early start, as the levels of H3N2 flu are now plateauing and may soon start to drop. Even though an early start can sometimes raise questions about a virus’s ability to transmit itself, experts believe it does not automatically mean a worse flu season.