After a punishing start to the year, health officials in Pennsylvania report that laboratory-confirmed flu cases are finally beginning to decline across the Commonwealth. However, the Department of Health (DOH) is urging residents not to let their guard down, as a second “peak period” remains a distinct possibility for late winter.
According to the latest data from the Pennsylvania Department of Health’s respiratory virus dashboard, flu activity has transitioned from “Very High” to “Moderate” over the last week.
While the trend is currently downward, the 2025–2026 season has already proven to be one of the most severe in the last five years.
Approximately 70,000 lab-confirmed cases have been reported since the season began in late September. Nearly 10,000 adults and more than 1,800 children have been hospitalized due to influenza complications. The DOH has confirmed 147 flu-related deaths in Pennsylvania residents so far this season.
A major driver of this year’s high volume is a new variant of Influenza A (H3N2) known as Subclade K. Dubbed “Super K” by some in the medical community, this strain features mutations that were not included in the original formulation of this year’s flu shot.
“Subclade K emerged after the vaccine components were finalized last February,” said a spokesperson for the Hospital & Healthsystem Association of Pennsylvania (HAP). “Because of this, we saw more breakthrough cases than usual, though the vaccine still remains the best tool for preventing the most severe outcomes like ICU admission and death.”
State health officials noted that while cases dropped from a high of 14,271 in early January to roughly 7,500 last week, Pennsylvania has a history of “double-peak” seasons. In early 2025, for example, cases dipped in January only to surge to nearly 29,000 cases in February.
