New Variant Subclade K: What to Know as Flu Season Starts

Ahead of the holidays, cases in the U.S. are already increasing in most states, according to data from the Centers for Disease Control and Prevention.

“Seasonal influenza activity continues to increase in most areas of the country,” the agency said in a weekly update. “Some indicators are elevated, but severity indicators remain low, and flu season is just starting.”

While the timing of the increased flu activity is similar to previous years, there is something unique about the season: a new variant.

The variant, called subclade K, has increased rapidly in Europe and several countries in East Asia, according to the Pan American Health Organization, or PAHO. The organization issued a call to strengthen surveillance and promote vaccination – particularly among older adults and people with risk factors.

“PAHO also urges countries to ensure timely clinical management of cases and prepare health services for the possibility of early, or more intense, respiratory disease activity,” it said.

Here is what to know about the flu season and new variant:

Five jurisdictions are experiencing high or very high levels of influenza-like illness that includes fever plus a cough or sore throat: New York City, New York state, Louisiana, Colorado and New Jersey, the CDC reports.

Nearly 3 million people have caught the flu already this season, according to agency estimates. An estimated 30,000 people have been hospitalized, and 1,200 died from flu so far this season.

Lab-confirmed flu hospitalization rates are higher now than they were at this time last year.

“It’s very difficult to predict a flu season, but right now we’re at the beginning of what we probably are going to see as a pretty severe influenza season driven primarily by this clade K virus,” Andrew Pekosz, a microbiology and immunology professor at Johns Hopkins University, told reporters during a briefing Tuesday.

The CDC recently reported the first death of a child from the flu this season.

Less than 40% of children have gotten a flu shot this year, according to CDC data. That’s lower than this time during the previous six seasons. Last flu season was the deadliest flu season for U.S. children in more than a decade, with 280 fatalities.

The new variant, subclade K, “is part of the natural variation process of seasonal influenza viruses,” according to PAHO.

In positive news, health authorities in the countries seeing the variant’s spread have not reported any increases in the severity of influenza cases.

But more people might be susceptible to infection because the variant “has mutations that are making it less able to be recognized by your body’s immune response,” according to Pekosz.

This year’s flu shot is a mismatch for the variant, as the shot was created before the strain was identified by researchers. But officials still recommend getting the shot since it appears to protect against severe infections.

“Although evidence on vaccine effectiveness for the current season remains limited, preliminary data from Europe indicate that vaccination continues to provide protection comparable to previous years against severe disease, including hospitalization,” PAHO said.

The CDC “recommends that everyone 6 months and older who has not yet been vaccinated this season get an annual influenza (flu) vaccine.”

Early estimates from the flu season in England found that hospitalizations remained in the expected ranges for children and adults, “suggesting that influenza vaccination remains an effective tool in preventing influenza-related hospitalizations this season,” according to the agency.

When the vaccine is a mismatch with the circulating strains, “vaccine effectiveness may be reduced but influenza vaccination continues to provide benefits, including: 1) protection against severe influenza illness, hospitalization, and death; 2) protection against other circulating influenza viruses represented in the influenza vaccines; and 3) help to reduce the overall community spread of influenza,” the CDC said.

The agency also recommends avoiding close contact with sick people, covering coughs and sneezes, washing hands and avoiding touching eyes, nose and mouth.