New Flu Variant Fuels Early, Aggressive Flu Season

The United States is experiencing an unusually early and aggressive flu season, marked by a significant increase in activity driven by a new variant of influenza A(H3N2), subclade K. Data from the CDC reveals that outpatient visits for flu-like symptoms have surpassed the epidemic threshold, confirming the season's official onset. This surge coincides with increased holiday travel and gatherings, facilitating rapid virus transmission.

Several regions, notably the Northeast, are reporting moderate to very high levels of flu activity. New York City is particularly affected, experiencing very high levels and a doubling of flu-related hospitalizations weekly. Public health officials are closely monitoring subclade K, a strain previously observed to cause busy flu seasons in other parts of the world. This variant was not directly included in this season's vaccines, though related strains offer some protection.

While flu seasons are inherently unpredictable, experts emphasize the importance of vaccination. Current data suggests vaccines offer between 30% and 75% protection against severe outcomes from H3N2, depending on the population. Public health authorities urge prompt vaccination and continued adherence to protective measures like mask-wearing in crowded indoor spaces, especially as case numbers rise.