A specialist has pinpointed three viruses that could pose a major threat to humanity by 2026, potentially leading to outbreaks in unforeseen locations or with unexpected severity.

In an insightful piece for The Conversation, Patrick Jackson, an assistant professor specializing in infectious diseases at the University of Virginia, highlighted the ever-present risk of widespread illnesses. He remarked that each new year could bring fresh viral dangers, as existing viruses continuously change. With the world warming and human populations growing, we find ourselves increasingly exposed to diverse viruses.

Jackson further noted that heightened global mobility allows viruses to swiftly traverse the globe with their human carriers. As a physician and researcher in the field of infectious diseases, he plans to monitor several viruses in 2026 that may be set to cause infections in previously unaffected areas or in larger than usual numbers.

Influenza A

Among these, Influenza A is a notable strain of the flu, being the only type known to cause pandemics. Jackson cautioned that we might be nearing an influenza A-driven pandemic, emphasizing its persistent threat. “Influenza A remains a constant concern,” he explained. “This virus infects various animal species and has the capability to rapidly mutate.”

The 2009 influenza pandemic, originating from the H1N1 variant or swine flu, resulted in over 280,000 deaths worldwide within its first year and continues to circulate today.

During 2009, an influenza pandemic stemming from the H1N1 variant – commonly referred to as swine flu – claimed over 280,000 lives globally within its first year. This strain continues to circulate to this day.

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The specialist also raised alarm over the highly-pathogenic avian influenza H5N1 subtype, commonly known as bird flu, which originates from influenza A. He explained: “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.

“The crossover of the virus from birds to mammals created major concern that it could become adapted to humans. Studies suggest there have already been many cow-to-human transmissions.

“In 2026, scientists will continue to look for any evidence that H5N1 has changed enough to be transmitted from human to human – a necessary step for the start of a new influenza pandemic. The influenza vaccines currently on the market probably don’t offer protection from H5N1, but scientists are working to create vaccines that would be effective against the virus.”

Mpox

According to Prof Jackson, mpox poses a threat that is “worldwide and liable to worsen”. Previously referred to as monkeypox, the pathogen predominantly affects rodents but periodically jumps to human hosts.

“Mpox is closely related to smallpox, and infection results in a fever and painful rash that can last for weeks,” he stated. “There are several varieties of mpox, including a generally more severe clade I and a milder clade II.”

A vaccine for mpox exists, though currently no proven treatments are available. During 2022, a worldwide outbreak of clade II mpox reached over 100 nations previously unfamiliar with the pathogen.

The outbreak was fuelled by person-to-person transmission via close physical contact, frequently during sexual activity. He continued: “While the number of mpox cases has significantly declined since the 2022 outbreak, clade II mpox has become established around the world.

“Several countries in central Africa have also reported an increase in clade I mpox cases since 2024. Since August 2025, four clade I mpox cases have occurred in the US, including in people who did not travel to Africa.” The UK Health Security Agency (UKHSA) has confirmed that clade I mpox infections have been identified within the UK as well.

Oropouche virus

This insect-transmitted virus is, in Prof Jackson’s assessment, “poised to spread”. It is transmitted by mosquitoes and tiny biting midges.

Prof Jackson explained: “Most people with the virus experience fever, headache and muscle aches. The illness usually lasts just a few days, but some patients have weakness that can persist for weeks. The illness can also recur after someone has initially recovered.”

Initially discovered in Trinidad and Tobago, it has subsequently expanded across broader regions of South America, Central America, and the Caribbean. He stated: “Cases in the United States are usually among travellers returning from abroad. In 2026, Oropouche outbreaks will likely continue to affect travellers in the Americas.

“The biting midge that carries Oropouche virus is found throughout North and South America, including the southeastern United States. The range of the virus could continue to expand.”

The UKHSA has cautioned that a “small number” of travel-related cases of Oropouche have been documented in the USA and Europe, including Britain.