The Conversation A new year might mean new viral threats.
Old viruses are constantly evolving. A warming and increasingly populated planet puts humans in contact with more and different viruses. And increased mobility means that viruses can rapidly travel across the globe along with their human hosts.
As an infectious diseases physician and researcher, I’ll be keeping an eye on a few viruses in 2026 that could be poised to cause infections in unexpected places or in unexpected numbers.
Influenza A – on the cusp of a pandemic
Influenza A is a perennial threat. The virus infects a wide range of animals and has the ability to mutate rapidly. The most recent influenza pandemic – caused by the H1N1 subtype of influenza in 2009 – killed over 280,000 people worldwide in its first year, and the virus continues to circulate today. This virus was often called swine flu because it originated in pigs in Mexico before circulating around the world.
Most recently, scientists have been monitoring the highly-pathogenic avian influenza H5N1 subtype, or bird flu. This virus was first found in humans in southern China in 1997; wild birds helped spread the virus around the world. In 2024, the virus was found for the first time in dairy cattle in the U.S. and subsequently became established in herds in several states.