After the British tabloid Daily Star published a story claiming that “Disease X” could cause a “devastating” pandemic in 2026, many Russian media outlets repeated the theme. The article mentioned mpox, rubella, bird flu and Oropouche virus as dangerous infections, but the experts cited by the newspaper did not describe them as “Disease X” itself.
The term “Disease X” was introduced by the WHO in 2018 to describe a new, previously unknown infection capable of triggering a pandemic. That is how the world encountered COVID-19: although coronaviruses were known before, the pandemic was caused by a new SARS-CoV-2 strain that, after mutations, became highly contagious and started spreading from person to person.
A Russian infectious disease specialist, who agreed to speak anonymously, said rubella is unlikely to become such a threat. According to the doctor, it is a well-studied and genetically stable virus that changes slowly, and the infection itself is controlled through vaccination. The specialist noted that incidence could rise if there were a mass refusal of vaccines or reduced vaccine access, but even then a pandemic scenario would be unlikely.
Mpox, in the source’s assessment, is also a poor fit for a global pandemic pathogen. It is a DNA virus, and such viruses mutate much more slowly than RNA viruses. In addition, the disease is mainly associated with countries in West and Central Africa, and, as the doctor explained, transmission between people requires very close and prolonged contact.
Oropouche virus, which causes a tropical infection, is spread through the bites of infected mosquitoes and midges. At present it does not spread from person to person, the illness is usually relatively mild, and fatal cases have barely been recorded. At the same time, the expert stressed that it is an RNA virus that continues to evolve, while increased travel to tropical countries and climate change could eventually affect how widely it spreads.
The specialist named H5N1 bird flu as the most serious candidate for continued monitoring. This subtype of influenza A has long been regarded as potentially risky because it already infects not only birds but also some mammals. Since 1997, when the first human infection from domestic poultry was confirmed, outbreaks have been regularly detected among workers at poultry and livestock farms.
As long as H5N1 has not been shown to spread from person to person, there are no grounds to classify it as the infection known as Disease X. But the virus’s continuing adaptation and capacity for genetic change mean it remains a dangerous pathogen that requires close observation.