The new year has just started, and 2026 is shaping up to have one of the worst influenza seasons on record.
The Centers for Disease Control and Prevention recently announced that outpatient visits for flu-like illness are at the highest they’ve been since the 1997-98 flu season. Pennsylvania hasn’t been hit as hard as some other areas of the country, with more than 13,000 cases as of the last week of December, according to the Pennsylvania Department of Health. However, its next-door neighbors, New York and New Jersey, have been hit especially hard, with New York reporting more than 71,000 cases as of Dec. 20.
The Lehigh Valley, however, is among the worst in the state for flu cases.
Lehigh County is just behind Philadelphia and Allegheny County in the number of flu cases overall, with 2,205 cases. It’s behind Erie and Monroe counties in terms of cases per capita, with 575 cases per every 100,000 people.
Northampton County is not far behind, with 1,701 confirmed cases and 542 cases per 100,000 people.
St. Luke’s and Lehigh Valley health networks both have seen a significant spike in patients hospitalized for influenza.
“I think everybody expects and certainly we expect, that whatever we’re saying right now is likely to be worse and that this is going to be a very bad respiratory virus year,” said Dr. Jeffrey Jahre, St. Luke’s chief emeritus of infectious diseases.
Jahre said that the reported case numbers for Pennsylvania may be well under the actual number of flu cases out there.
As of Tuesday, about 1,840 adult and 515 children were currently hospitalized with the flu in Pennsylvania hospitals, according to state data.
Dr. Alex Benjamin, chief infection control and prevention officer for LVHN, part of Jefferson Health, said the network was seeing a high number of cases, though not to the point it is overwhelmed.
Jahre said that in the last two weeks, St. Luke’s has seen 38 patients hospitalized with flu, several of whom were critically ill. No deaths have been reported.
What’s driving the high flu cases?
Part of what’s so different about this season is a new mutation of flu, called subclade K.
A type A flu, Benjamin said that it appears to more effectively evade the immune system and provoke more severe symptoms. Jahre said that this evasiveness also allows it to spread more easily because few people have an immune memory to something like it.
There has been some speculation that the emergence of subclade K could cause a so-called “super flu,” but scientists and infectious disease experts point out that flu is always mutating and changing, and while subclade K is different, it isn’t any more dangerous than other strains of the flu.
That said, this year’s flu vaccine is not a great match for the virus. However, even a good match for the flu vaccine only has about 50% efficacy at preventing a flu infection. It is, however, most effective at preventing severe flu-related illness, Jahre said.
Jahre said what is unfortunate is that vaccine uptake this year has been quite low, with less than 40% of adults vaccinated against flu and about 35% of children.
“There’s still very good evidence to show that you can get some benefits from the vaccine against this strain in terms of avoiding some of the worst consequences of the disease,” Jahre said. “Those worst consequences include hospitalization and death. Even though you still may come down with a fairly major form of influenza, the chances of you dying or being hospitalized are reduced if you have received a vaccine.
“Virtually everyone over the age of 6 months for all practical purposes, and there are very few exceptions, should have the influenza vaccine. And is it too late to get it? No, it’s not.”