New ‘subclade K' flu variant circulates widely, health officials urge vaccination

A new variant of the flu virus is spreading rapidly across the United States just as holiday travel and gatherings begin.

The variant, known as H3N2 subclade K, has become the dominant flu virus in recent weeks in the U.S. as reported by health officials. It is the main reason for seasonal flu these days, alongside influenza A subtype H1N1 and influenza B viruses.

Genetic analysis conducted by Centers for Disease Control and Prevention (CDC) highlights around 90% of recently sampled H3N2 viruses belong to this new subclade.

The flu cases are increasing nationwide with CDC’s latest data indicating 4.6 million illnesses, 49,000 hospitalizations, and 1,900 deaths.

There is a sharp increase in some states with New York reporting a 93% weekly surge in flu hospitalizations in late November.

CDC data also reports that 89% of the H3N2 virus cases belonged to “subclade K.”

Symptoms of new flu strain

The symptoms of the mutated H3N2 flu strain is similar to usual influenza A strains, including:

• Fever
• Chills
• Body aches
• Headaches
• Extreme fatigue
• Congestion or runny nose
• Coughing
• Vaccine effectiveness

Despite the genetic mismatch, health authorities strongly stress that vaccination remains a critical tool. The current shot is a good match for other circulating strains, such as H1N1 and still provides a crucial protection against severe illness, hospitalization, and death from the new variant.

The effectiveness of the vaccine is evident from early data from England which is also battling against the same subclade K variant. 

According to it, the vaccine maintained 70-75% effectiveness against flu hospitalization in children and 30-40% in adults.

Health departments are urging people to follow preventive measures ahead of the holiday season. It includes getting vaccinated, staying home if sick, considering wearing a mask, and washing hands frequently.