Flu cases are rapidly increasing across the United States, primarily driven by a new variant known as subclade K. This uptick in infections comes just ahead of the holiday season, where extensive travel is expected to contribute to further spread. The variant has already caused early outbreaks in other countries, including the United Kingdom, Japan, and Canada. The Centers for Disease Control and Prevention (CDC) has reported that flu seasons typically start in December, and as of now, more than half of the states are experiencing high or very high levels of flu-related illnesses.
The CDC has provided an estimate indicating that this flu season has already seen at least 7.5 million illnesses, 81,000 hospitalizations, and approximately 3,100 deaths, including at least eight fatalities among children. This data was compiled up to December 20, prior to the major holiday gatherings that often lead to increased transmission rates.
New York has been particularly affected, with the state’s health department announcing that the week ending December 20 marked the highest number of flu cases recorded in a single week since 2004, reaching a total of 71,000 cases. While it is still too early to assess if this flu season will be as severe as last winter’s, health experts are urging the public to get vaccinated to mitigate the risk of severe illness, even if they do contract the virus.
Although this year’s influenza vaccine may not perfectly match the circulating subclade K strain, preliminary analyses from the U.K. indicate that it may still provide partial protection, thus reducing the risk of hospitalization related to flu symptoms. As of now, only around 42% of adults and children in the U.S. have received a flu vaccination this season, highlighting a gap in public health efforts.
Subclade K is a mutated version of the H3N2 strain, one of the two subtypes of Type A flu. While the mutations present in subclade K do not classify it as a completely new type of flu, they are significant enough to allow it to evade some immunity provided by this year’s vaccine. Andrew Pekosz, a virus expert at Johns Hopkins Bloomberg School of Public Health, emphasized that further research is needed to determine whether the subclade K variant spreads more easily or is indeed more virulent.
The CDC cautions that while flu seasons led by any variant of H3N2 tend to result in more widespread infections and serious health complications, the overall impact of subclade K is still being assessed. Prescription medications for flu are available and commonly recommended for individuals at high risk for complications; however, these treatments are typically most effective when administered within the first day or two of symptom onset.
The CDC and various medical authorities recommend flu vaccinations for nearly everyone aged six months and older. Despite significant misinformation circulating about vaccines, the guidance surrounding flu vaccinations remains unchanged. The flu virus can be particularly dangerous for specific demographics, including individuals aged 65 and older, pregnant women, young children, and those with chronic health conditions such as asthma, diabetes, and heart disease.
This year’s flu vaccine is formulated to protect against three strains of influenza. Despite concerns regarding the new H3N2 variant, the vaccine appears to provide a suitable match against other strains, such as H1N1 and Type B flu, which may also be present this season. Vaccination options include shots for all age groups, as well as the nasal spray FluMist for individuals aged 2 to 49. Notably, some people may now have the opportunity to self-administer FluMist at home for the first time this flu season.
