Flu Cases Surging In NY: What To Know About Subclade K Mutation

NEW YORK — The predicted surge of influenza cases, driven by the new “subclade K” mutation, is hitting New York emergency rooms as holiday get-togethers put people in close spaces where the flu virus can easily spread.

Flu activity is high or very high in 48 states and jurisdictions, according to the latest data from the Centers for Disease Control and Prevention. At least 11 million people have gotten sick, and 5,000 people have died from the flu this season as vaccination rates wane. At least nine of those who died were children.

The CDC said the current influenza wave is expected to last several weeks. The agency also noted that RSV activity is elevated in many areas of the country, with emergency room visits and hospitalizations increasing in children under 4. COVID-19 activity is low but increasing nationally.

According to a weekly influenza surveillance report put out by the CDC, New York's activity level is currently "very high."

And, according to the New York State Department of Health on January 2, the state was experiencing the highest number of flu hospitalizations recorded in a single week.

"We are having a more severe flu season than prior years, almost 1,000 more people were admitted to a hospital during this most recent 7-day period compared to the prior week," State Health Commissioner Dr. James McDonald said. "There is still time to get a flu shot and remember, flu can be treated with antiviral medication if started within 48 hours of symptom onset and your doctor deems appropriate."

Symptoms include fever or feeling feverish/chills, cough, sore throat, runny or stuffy nose, muscle or body aches, headache, tiredness, vomiting or diarrhea even though it is more common in children, the NYSDOH said.

The department's most recent data shows a total of 4,546 hospitalizations, almost 1,000 more than the prior week.

Last week, the department announced that the state experienced the highest number of flu cases ever recorded in a single week.

Last month, the department declared that influenza is prevalent in New York State. The declaration requires health care facilities and agencies ensure that their personnel who have not received this year's flu vaccine wear masks in areas where patients and residents may be present.

The number of flu cases reported has risen in recent years with more laboratories testing and reporting results, and with multi-pathogen panels becoming the primary way to test individuals presenting with respiratory symptoms, the NYSDOH said. But this record number underscores that the season is impacting more people than in other recent years. Flu season typically peaks in January, the NYSDOH said.

It is not too late to get vaccinated against influenza, and the flu vaccine is widely available to those 6 months and older, the NYSDOH said. Young children, pregnant women, people with certain chronic medical conditions and those ages 65 and older are most at risk of developing serious complications from the flu, the DOH said.

To treat the flu, there are antiviral medications that can be prescribed by health care providers, which can reduce the length and severity of the illness but must be administered close to the onset of symptoms, the NYSDOH said.

The seasonal influenza vaccine remains the best protection against serious illness and death from the flu. It can help reduce absences from work, school and extracurricular activities, and provides protection for the most vulnerable members of families and communities, the DOH said.

In addition to getting the flu vaccine, simple preventive actions can help stop the spread of influenza and other respiratory viruses, the NYSDOH ssaid.

• Wash hands often with soap and water for at least 20 seconds. If soap and water are not available, use an alcohol-based hand sanitizer.
• Avoid close contact with people who are sick.
• Stay home when sick.
• Cover cough or sneeze with a tissue, then throw the tissue in the trash.
• Clean and disinfect frequently touched objects and surfaces.

It’s influenza that is causing the most concern among health care providers. This year’s flu season is more serious for a few reasons. One is that the subclade K mutation emerged after the vaccine was chosen for the Northern Hemisphere, last February. Once the mutation became established, there wasn’t time to develop a better-matched vaccine. That leaves more people susceptible because the virus has found a way to evade pre-existing immunity from either an infection or vaccination.

Influenza A strain H3NS has mutated seven times, making the flu a more serious threat than in years past. It caused a severe flu season around the world, including in the U.K., Canada, Japan and Australia. Recent CDC data shows that nearly all virus samples since late September were the subclade K mutation.

“Right now we’re seeing clade K everywhere we are seeing influenza” in the U.S., Andrew Pekosz, a professor and vice chair of the department of molecular microbiology and immunology at the Johns Hopkins Bloomberg School of Public Health, said in a pre-Christmas news conference.

Even with a mismatch, health experts advise people to get flu shots, saying they should provide some protection against severe disease and death. The CDC recommends influenza vaccination for everyone 6 months and older who has not yet been immunized this flu season. Currently, approximately 130 million doses of the flu vaccine have been distributed across the U.S.

In mid-December, the CDC estimated 42 percent of Americans had gotten their flu shots. Rates vary greatly by age, with around 60 to 70 percent of older adults over age 65 getting their shots. Coverage varies from year to year, but generally falls far short of the 70 percent goal for herd immunity. Some flu seasons have seen vaccine coverage around 47 percent.

Pekosz, speaking at a Dec. 23 news conference, said the mutations “may allow it to evade some but not all of the influenza-vaccine-induced protection.”

“We’re still in the middle of trying to figure out whether it’s producing worse illness or whether what we’re seeing is a large number of cases that are increasing, and then there’s a correspondingly similar increase in terms of the severe illness,” he said.

The advice to get vaccinated was still on the CDC website on Monday, when the agency announced a major overhaul of the childhood vaccine schedule. Flu shots will be recommended in shared clinical decision-making, which means patients and providers will discuss vaccination before proceeding.

This approach was adopted last year for most COVID-19 and hepatitis B vaccine recommendations.