The year 2026 may be marked by new global alerts related to emerging viruses. Experts point out that, since the COVID-19 pandemic, a combination of risk factors has created favorable conditions for the evolution and spread of infectious agents, at an accelerated pace.
Factors Fueling Viral Emergence
Key factors contributing to this increased risk include global warming, population growth, and increased human mobility. These elements expand contact between people, animals, and previously isolated environments, facilitating the emergence and propagation of new viruses.
Viruses on the Radar for 2026
Recent analysis highlights three viruses deserving special attention in 2026: avian influenza H5N1, mpox, and the Oropouche virus. The goal is to anticipate strategic surveillance actions in the face of the threat posed by these viruses, which have recently expanded their area of circulation and are causing concern among health authorities worldwide.
Oropouche Virus: A Growing Threat
First identified in 1950, the Oropouche virus is transmitted by mosquitoes and causes symptoms similar to the flu. For decades considered restricted to the Amazon region, the virus has become an increasing threat in Brazil and other countries in the Americas.
Since the 2000s, Oropouche has been expanding into areas of South, Central, and the Caribbean, linked to the adaptation of the main vector to wider and more urbanized environments. The situation worsened from 2023, with the virus’s circulation gaining strength in Brazil. Data from the Pan American Health Organization indicated that, as of August 2025, Brazil accounted for 90% of cases recorded in the Americas, with the disease occurring in 20 states. During the peak, five deaths were confirmed, four in Rio de Janeiro and one in Espírito Santo.
Currently, there is no preventive vaccine or specific treatment for Oropouche, increasing risks in case of infection and raising alerts for health authorities. In response, the World Health Organization (WHO) presented a proposal on January 5, 2026, to accelerate the development of prevention and control tools against the virus, reinforcing the need for international surveillance and coordinated response.
Avian Influenza H5N1: A Potential Pandemic Strain
Influenza A is historically considered a public health threat due to its high mutation rate. Over time, the disease has caused pandemics, the most recent in 2009, caused by the H1N1 strain, resulting in over 280,000 deaths in the first year, according to international estimates.
Currently, experts are most concerned about the H5N1 strain, responsible for avian influenza. Previously associated almost exclusively with birds, the circulation of the virus has become even more concerning after the identification, in 2024, of infections in dairy cows in the United States, indicating an expansion of the host spectrum.
In Brazil, a case of avian influenza was confirmed in 2025 on a commercial farm. The main concern of health authorities is that the virus manages to adapt to transmission between humans, a hypothesis that has not yet been confirmed. Data from the Centers for Disease Control and Prevention (CDC) indicate that, since 2024, 71 human cases of the disease and two deaths have been recorded, with no evidence of sustained community transmission.
Given the potential risk, specific vaccines against the H5N1 strain are under development, as currently available formulations do not offer adequate protection. In Brazil, the Butantan Institute is conducting preclinical safety studies for a vaccine aimed at the new strain, as part of preparedness strategies for a possible health emergency.
Mpox: A Resurgent Concern
Considered a rare disease for decades, mpox had, for a long time, circulation practically restricted to specific regions of Africa. This scenario changed in 2022, when the clade IIb strain spread rapidly and was recorded in more than 100 countries.
The virus is transmitted mainly through close physical contact, often associated with sexual relations. Since 2024, health authorities have observed a significant increase in cases in Central Africa, a region that has too confirmed infections by the clade I strain, considered more severe.
Currently, a vaccine is available against mpox, but there is no specific treatment defined for the disease. Experts assess that the evolution of the virus and its ability to adapt may pose new challenges to public health throughout 2026.
Other Potential Viral Threats in 2026
Beyond the three viruses highlighted as priorities by experts, other diseases may also pose challenges to public health in 2026. These include chikungunya, which has shown significant numbers in recent years, with over 445,000 suspected cases worldwide and 155 deaths as of September 2025. Measles has also become a concern for health authorities in different countries.
Experts also warn of the possibility of HIV advancing in the coming years if cuts in international health cooperation programs persist, which are fundamental for prevention, diagnosis, and treatment of infection in low- and middle-income countries.
Frequently Asked Questions
What is the biggest viral threat in 2026?
Experts identify avian influenza H5N1, mpox, and the Oropouche virus as significant threats due to their potential for spread, and impact.
Is there a vaccine for the Oropouche virus?
Currently, there is no preventive vaccine or specific treatment for the Oropouche virus.
What is being done to address the H5N1 threat?
Vaccines specific to the H5N1 strain are under development, and surveillance efforts are being increased to monitor potential human transmission.
Where can I find more information about these viruses?
Refer to the World Health Organization (WHO) and the Pan American Health Organization (PAHO) for the latest updates and information.
What can individuals do to protect themselves?
Practice good hygiene, stay informed about outbreaks in your area, and follow public health recommendations.
