Patrick Jackson, University of Virginia

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.

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 – worldwide and liable to worsen

Mpox virus, formerly called monkeypox virus, was first discovered in the 1950s. For many decades, it was seen rarely, primarily in sub-Saharan Africa. Contrary to its original name, the virus mostly infects rodents and occasionally crossed over into humans.

Mpox is closely related to smallpox, and infection results in a fever and painful rash that can last for weeks. There are several varieties of mpox, including a generally more severe clade I and a milder clade II. A vaccine for mpox is available, but there are no effective treatments.

In 2022, a global outbreak of clade II mpox spread to more than 100 countries that had never seen the virus before. This outbreak was driven by human-to-human transmission of the virus through close contact, often via sex.

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 U.S., including in people who did not travel to Africa.

It is unclear how mpox outbreaks in the U.S. and abroad will continue to evolve in 2026.

Oropouche virus – insect-borne and poised to spread

Oropouche virus was first identified in the 1950s on the island of Trinidad off the coast of South America. The virus is carried by mosquitoes and small biting midges, also known as no-see-ums.

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.

There are many unanswered questions about the Oropouche virus and the disease it causes, and there are no specific treatments or vaccines. For decades, infections in people were thought to occur only in the Amazon region. However, beginning in the early 2000s, cases began to show up in a larger area of South America, Central America and the Caribbean. Cases in the United States are usually among travelers returning from abroad.

In 2026, Oropouche outbreaks will likely continue to affect travelers 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.

Even more viral threats

A number of other viruses pose a risk in 2026.

Continuing global outbreaks of chikungunya virus may affect travelers, some of whom may want to consider getting vaccinated for this disease.

Measles cases continue to rise in the U.S. and globally against the backdrop of decreasing vaccination rates.

HIV is poised for a resurgence, despite the availability of effective treatments, due to disruptions in international aid.

And as-yet-undiscovered viruses can always emerge in the future as humans disrupt ecosystems and travel around the world.

Around the world, people, animals and the wider environment are dependent on each other. Vigilance for known and emerging viral threats and the development of new vaccines and treatments can help keep everyone safe.

Patrick Jackson, Assistant Professor of Infectious Diseases, University of Virginia

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Aaron Pilkington, University of Denver

Perhaps no one outside of Venezuela or Cuba should care more about the U.S. capture of nominal President Nicolás Maduro than the Islamic Republic of Iran’s supreme leader, Ali Khamenei.

Khamenei and his regime are in trouble, and it’s not clear how they would survive should the Trump administration decide to support the millions who want a new government system without Khamenei and his ilk.

Iran has no state allies that would be willing to intervene militarily on its behalf. Further, its once-powerful network of partner and proxy militias – Lebanese Hezbollah, the Houthi rebels in Yemen, and other members of the Axis of Resistance – has been rendered incapable or reluctant to get involved. And Iran’s economy is in shambles in the midst of an ongoing water crisis with no relief in sight.

Further, the Iranian people have again taken to the streets to air their grievances against harsh economic conditions as well as government corruption, mismanagement and hypocrisy, echoing similar conditions to Venezuela in recent years.

Lastly, President Donald Trump has returned his attention to Iran. On Jan. 2, Trump warned Khamenei that if his forces violently suppress protesters, Iran would be “hit very hard” by the U.S.

Trump’s warning and show of solidarity will likely embolden protesters, which will almost certainly cause Iran’s internal security to crack down harder, as has happened in the past. Such U.S. intervention could lead to the overthrowing of the ayatollah, intended or not. Furthermore, Maduro’s fate demonstrates that the Trump administration is willing to use military force for that purpose if deemed necessary.

As an analyst of Middle East affairs focusing on Iran, I believe that these conditions place Khamenei’s regime under greater threat today than perhaps any other time in its 46-year history.

Growing threats, internal and external

If Khamenei hopes to survive politically or mortally, I believe he has three options.

First, he could capitulate to U.S. demands to halt Iran’s nuclear enrichment program. Second, Iran could sprint toward a nuclear bomb. Lastly, he could flee.

In hopes of restoring deterrence, Khamenei could also continue rebuilding his country’s military capabilities, which were significantly degraded during the June 2025 12-day war in which Israel and the U.S. aimed to destroy Iran’s nuclear capability.

Israel is eager to stifle Iran’s reconstitution plans, protests are spreading and growing more intense, and Trump – through hostile rhetoric and offensive military action – has put Khamenei on notice.

Khameini’s problems aren’t his alone. The revolutionary theocratic system of government that he leads is in danger of falling. And his military and internal security apparatus may not have the time or ability to address its growing and interrelated internal and external threats simultaneously.

There are two fundamental factors analysts like me consider when assessing enemy threats: offensive capability to inflict damage and hostile intentions to use these capabilities to harm enemies.

Determining offensive capability involves evaluating the quality of a country or organization’s complete arsenal – air, ground, maritime, cyber and space capabilities – and how trained, disciplined, integrated and lethal their forces might be. Determining intentions involves evaluating if, when and under what conditions offensive capabilities will be used to achieve their goals.

If states hope to survive when they come under such pressure, their defense strategy should account for differences between their own military capability and the enemy’s, especially if enemies intend to attack. Or states need to convince enemies to be less hostile, if possible.

Maduro’s mistake was his inability to defend against a far superior U.S. military capability while believing that U.S. leaders would not remove him from office. Maduro gambled and lost.

Bad choices

Iran’s supreme leader faces a similar conundrum: First, there is no foreseeable path that allows Tehran to produce or acquire the military capabilities necessary to deter Israel or defeat the United States, unless Iran develops a nuclear weapon.

And decades of mutual hostility, the memory of Iran’s once-clandestine nuclear weaponization program and recent Iranian lawmaker calls to develop nuclear bombs minimizes the prospect that U.S. leaders view Khamenei’s intentions as anything but hostile.

But as the clear weaker party, it is in Tehran’s interest to change Trump’s mind about Tehran’s hostile intent. The way to do that would be by abandoning nuclear enrichment.

In terms of threat analysis, the regime’s oft-repeated chants of “Death to America” and “Death to Israel” perhaps have sent an easily misinterpreted message: that Iran’s hostile leaders intend to destroy the U.S. and Israel. But they simply lack the capability, for now.

President Theodore Roosevelt famously said “speak softly and carry a big stick; you will go far.” Today, he might say that Khamenei is unwise for speaking with such vitriol considering the size of Iran’s stick. The United States and Israel possess military capabilities far superior to Iran’s – as demonstrated by the 12-day war – but they did not then share the same intent. Though both Israel and the U.S. operations shared the objective of neutralizing Iran’s nuclear capability, Israel’s objectives were more broad and included targeting senior Iranian leaders and destabilizing the regime.

To Khamenei’s momentary personal and institutional fortune, Trump immediately called for a ceasefire following U.S. B-2 strikes on Iranian nuclear facilities, delineating the United States’ narrower objectives that at the time did not include regime change in Iran.

But that was before U.S. forces removed Maduro from Caracas and before the outbreak of protests in Iran, both of which coincide with Israel’s signaling preparations for Round 2 against Iran.

Iran without Khamenei?

During Trump’s Dec. 29 press conference at Mar-a-Lago with Israeli Prime Minister Benjamin Netanyahu, he warned that the U.S. could “knock the hell” out of Iran if the country reconstitutes its nuclear facilities.

This is separate from the ominuous warning that the U.S. could intervene on behalf of Iranian protesters; it would almost certainly differ in scale.

Nevertheless, a potential U.S. intervention could embolden protesters and further undermine and destabilize the Islamic Republic regime. Khamenei has predictably scoffed at and dismissed Trump’s warning.

I believe this is a serious mistake.

Secretary of State Marco Rubio warned on Jan. 3, 2025, that Khameini should not “play games” as Maduro did. Khamenei, Rubio said, should take Trump’s warnings seriously. I agree.

If Iran refrains from violent crackdowns on protesters, there is a chance that anti-government protestors overthrow the government. But the supreme leader’s chances of surviving a popular uprising are probably greater than surviving an unbridled U.S. or Israeli military intent on ushering in a new – post-Islamic Republic – Iran.

Otherwise, Khamenei has to address superior U.S. and Israeli military capability, quickly. But Iran is broke, and even if sanctions were not continuously strangling Iran economically, the country could probably never purchase its way to military parity with the U.S. or Israel.

Alternatively, Iran could determine that it must move quickly to develop a nuclear weapon to mitigate U.S. and Israeli military capabilities and deter future aggression. However, it is extremely unlikely Iran could do this without U.S. and Israeli intelligence discovering the project, which would immediately trigger an overwhelming military campaign that would likely expedite regime change in Iran.

And like Maduro, the supreme leader is utterly alone. None of Maduro’s closest partners – China, Russia, Cuba and even Iran – were willing to fight in his defense, despite weeks of forewarning and U.S. military buildup near Venezuela.

Under these circumstances, it may be impossible for Khamenei to address overwhelming U.S. and Israeli military capabilities. He could, however, reduce the threat by doing what is necessary to ensure the United States’ objectives for Iran remain narrow and focused on the nuclear program, which may also keep Israel at bay.

However, Khamenei would have to demonstrate unprecedented restraint from cracking down violently on protesters and a willingness to give up nuclear enrichment. Due to historical animosity and distrust toward the U.S., both are unlikely, increasing, I believe, the probability of a forthcoming Iran without Khamenei.

Aaron Pilkington, Fellow at the Center for Middle East Studies, University of Denver

This article is republished from The Conversation under a Creative Commons license. Read the original article.