An infectious diseases expert has issued a stark warning, identifying three specific viruses that could pose a serious and widespread threat to human health throughout 2026. Professor Patrick Jackson, an assistant professor of infectious diseases at the University of Virginia, cautions that these pathogens are poised to cause infections in unexpected locations or at alarming new scales.
Why New Viral Threats Are Emerging
In an analysis for The Conversation, Professor Jackson explained that the risk of widespread illness is a constant and evolving danger. "A new year might mean new viral threats," he stated, highlighting several key factors driving this risk. Old viruses are continuously mutating, while a warming and more populated planet increases human contact with diverse viruses. Furthermore, our highly mobile global society allows these viruses to travel rapidly across continents alongside their human hosts.
As a physician and researcher, Professor Jackson said he will be closely monitoring three particular viruses in the coming year.
Influenza A: On the Cusp of a Pandemic
The first and perhaps most familiar threat is Influenza A, the only type of influenza known to cause pandemics. Professor Jackson described it as a "perennial threat" due to its ability to infect a wide range of animals and mutate quickly. He warned that we are currently "on the cusp of a pandemic" caused by this virus.
He pointed to the 2009 H1N1 (swine flu) pandemic, which killed over 280,000 people globally in its first year, as a stark reminder of its potential. Particular concern now surrounds the highly pathogenic avian influenza H5N1 subtype (bird flu). First detected in humans in 1997 in southern China, it spread worldwide via wild birds. A significant development occurred in 2024 when the virus was found in US dairy cattle, establishing itself in herds across several states.
This crossover from birds to mammals raises major fears that H5N1 could adapt to humans. Studies suggest numerous cow-to-human transmissions have already occurred. In 2026, scientists will vigilantly watch for any sign that the virus has mutated sufficiently to enable sustained human-to-human transmission—the crucial step for a new pandemic. Current flu vaccines offer little protection against H5N1, though researchers are actively developing effective alternatives.
Mpox: A Global Problem Set to Worsen
The second virus on the watchlist is mpox (formerly monkeypox). While it primarily infects rodents, it can cross over to humans, causing fever and a painful rash that lasts weeks. Professor Jackson stated mpox is now "worldwide and liable to worsen."
There are several varieties, including a generally more severe clade I and a milder clade II. A 2022 global outbreak of clade II spread to over 100 countries that had never reported the virus before, driven largely by human-to-human transmission through close contact. Although case numbers have declined since that peak, clade II mpox is now established globally.
Alarmingly, since 2024, several central African countries have reported increases in the more severe clade I mpox. From August 2025, four clade I cases were detected in the United States, including in individuals with no travel history to Africa. The UK Health Security Agency (UKHSA) has also confirmed detecting clade I mpox cases within the UK. While a vaccine exists, there are currently no fully effective treatments for the disease.
Oropouche Virus: Poised to Spread
The third emerging threat is the insect-borne Oropouche virus, which Professor Jackson describes as "poised to spread." Carried by mosquitoes and biting midges, infection typically causes fever, headache, and muscle aches for a few days, though weakness can persist for weeks and the illness can recur.
Originally identified in Trinidad and Tobago, the virus has expanded its reach across South America, Central America, and the Caribbean. Cases in the United States and Europe, including the UK, have so far been linked to travellers returning from affected regions. The UKHSA has noted a "small number" of such travel-associated cases.
Professor Jackson warns that in 2026, outbreaks will likely continue to affect travellers in the Americas. Crucially, the biting midge that carries the virus inhabits all of North and South America, including the southeastern United States, meaning the virus's geographic range has significant potential for further expansion.
The expert's analysis serves as a sobering reminder that in our interconnected world, vigilance and preparedness against evolving viral threats remain paramount for public health security in 2026 and beyond.
