Old viruses are constantly evolving. As the Earth warms and the population grows, humans are exposed to different types of viruses. Increased travel also means that viruses can spread rapidly around the world with their human carriers.
What are the most prominent “viruses” that may cause infection in unexpected places or in unexpected numbers in 2026?
Influenza A – on the verge of a pandemic
Influenza A is a constant threat. This virus infects a wide range of animals and has the ability to mutate rapidly. The last influenza pandemic killed more than 280,000 people worldwide in its first year, and the virus continues to spread to this day.
This virus was often called “swine flu” because it originated in pigs in Mexico before spreading around the world.
Bird flu
Scientists have recently been closely monitoring the highly contagious “H5N1” strain of bird flu.
This virus was first detected in humans in southern China in 1997, and wild birds have contributed to its spread around the world. In 2024, the virus was first detected in cattle in the United States, and then settled in cattle herds in several states.
The transmission of the virus from birds to mammals has raised increasing concerns that it may adapt to humans. Studies indicate that there have been several cases of transmission from cows to humans.
In 2026, scientists will continue to look for any evidence that “H5N1” has changed enough to be transmitted from person to person, a necessary step to start a new influenza pandemic. Current influenza vaccines on the market are unlikely to provide protection against “H5N1,” but scientists are working to develop effective vaccines against this virus.
Monkeypox Virus – Globally Spread and Worsening
Monkeypox virus was first discovered in the 1950s. For decades, it was rare, especially in sub-Saharan Africa. The virus mostly infects rodents and sometimes spreads to humans.
Monkeypox virus is closely related to smallpox, and infection with it leads to a rash accompanied by fever and pain that can last for weeks. There are several types of monkeypox virus, including type one, which is generally more dangerous, and type two, which is less dangerous. A vaccine for monkeypox virus is available, but there are no effective treatments.
In 2022, a global epidemic of type two monkeypox virus spread to more than 100 countries that had never seen the virus before. This outbreak resulted from human-to-human transmission of the virus through direct contact, often through sexual contact.
Despite the marked decrease in the number of cases of monkeypox virus (“mpox”) since the 2022 outbreak, the second pattern has spread globally. Several countries in Central Africa have also reported an increase in cases of the first pattern since 2024. As of August 2025, 4 cases of the first pattern have been recorded in the United States, including cases of people who have not traveled to Africa.
It remains unclear how outbreaks of monkeypox virus in the United States and abroad will develop during 2026.
Oropouche Virus – Transmitted by Insects and Preparing to Spread
Oropouche virus was first identified in the 1950s on the island of Trinidad off the coast of South America. The virus is transmitted by mosquitoes and biting midges, also known as “no-see-ums.”
Most people infected with the virus suffer from fever, headache, and muscle pain. The disease usually lasts only a few days, but some patients suffer from weakness that can last for weeks. The disease can also return after the initial recovery.
