Northern Hemisphere Faces “Tripledemic” as RSV, Flu, and COVID-19 Drive Winter Surge in Hospitalizations

As winter sets in across the Northern Hemisphere, countries in North America, Europe, and East Asia are reporting rising hospitalization rates due to a concurrent surge in respiratory syncytial virus (RSV), seasonal influenza—predominantly the A(H3N2) strain—and ongoing circulation of SARS-CoV-2 variants, particularly KP.3 and KP.2.

Public health agencies from the United States, the United Kingdom, Germany, Japan, South Korea, and Canada have documented a steady increase in outpatient visits and hospital admissions since late October, especially among young children, older adults, and individuals with underlying health conditions. The simultaneous circulation of these three viruses has led health officials to describe the situation as a “tripledemic.”

In the U.S., the Centers for Disease Control and Prevention (CDC) reports that RSV activity is now at seasonal peak levels in most regions, while influenza positivity rates have doubled over the past four weeks, with A(H3N2) accounting for over 85% of confirmed flu cases. Hospital bed occupancy rates have risen modestly but remain below critical thresholds.

Similarly, the European Centre for Disease Prevention and Control (ECDC) notes elevated RSV and flu activity across Western and Southern Europe, with pediatric intensive care units in several countries operating at higher-than-usual capacity. In East Asia, Japan and South Korea have activated seasonal respiratory disease response protocols, including expanded testing and triage systems.

Despite the increased pressure, health systems have so far avoided major disruptions, thanks to robust surveillance, earlier vaccination campaigns, and lessons learned from previous pandemic winters. Updated flu vaccines and the rollout of RSV immunizations—such as nirsevimab for infants and arexvy for older adults—have helped mitigate severe outcomes.

Authorities continue to encourage vaccination against influenza and COVID-19, promote RSV prophylaxis for eligible groups, and advise the public to practice preventive measures including hand hygiene, staying home when symptomatic, and wearing masks in crowded indoor settings.

While the “tripledemic” has intensified seasonal respiratory illness burdens, current data indicate that healthcare systems remain resilient and capable of managing the increased demand.