Flu activity has escalated to high or very high levels in the Greater Philadelphia area following the winter holidays, as reported by federal and state health data. This surge has seen local hospitals and healthcare systems experiencing a notable increase in outpatient visits and emergency room admissions. Both children and adults are presenting with symptoms such as fevers, coughs, respiratory issues, vomiting, and other gastrointestinal complaints.
A new variant of the influenza virus, identified as a subclade circulating globally, is believed to be the driving force behind the rise in cases in the U.S., indicating the potential for a prolonged and challenging flu season. Dr. Henry Fraimow, an infectious disease specialist at Cooper University Health Care, emphasizes the importance of receiving flu vaccinations, stating, “there’s still a benefit to getting your flu shots now, because we just don’t know how long this season is going to last.”
From the week of Thanksgiving to the beginning of January, infection rates in Pennsylvania, New Jersey, and Delaware rose sharply from minimal to moderate levels, according to the U.S. Centers for Disease Control and Prevention. In the week ending January 3, Pennsylvania reported over 14,300 positive flu tests, a stark increase compared to approximately 1,690 cases in the week ending November 29. New Jersey alone saw hospitalizations exceed 550 during the week of Christmas, marking a record high in flu-related admissions in recent years.
Much of the flu cases are linked to influenza Type A, subtype H3N2, which has been classified as the “super flu” variant. However, there is no evidence that it leads to more severe infections. Current seasonal flu vaccines still provide some protection against H3N2 variants, with Dr. Fraimow noting that while the vaccines are effective in preventing severe outcomes such as hospitalization and death, they may not be as successful in preventing illness among individuals who typically do not contract the flu.
This subclade has caused unusually long flu seasons in regions such as Australia and New Zealand, characterized by an abnormal surge leading up to Christmas during their summer months. Dr. Fraimow stresses the importance of monitoring the situation closely in the U.S., as the behavior of the virus in other parts of the world may provide critical insights into potential developments domestically.
These findings underscore the importance of vaccination during a time when flu cases are spiking, offering hope for mitigating the spread and impact of illness in the region.