What is ‘Disease X’? COVID experts warn it could cause deadlier pandemic

The World Health Organization keeps a short list of “priority diseases” that could cause the next deadly pandemic.

Most of the diseases are already known to us — Ebola, SARS and Zika made the cut — but the final entry has the terrifying name “Disease X.”

The term Disease X is used by the WHO as a placeholder to describe a disease that’s unknown to medical science as a cause of human infections.

And as a new disease agent — whether it’s a virus, a bacterium, a fungus or other agent — there likely won’t be any vaccines or few, if any, treatments available.

“This isn’t the stuff of science fiction,” Dr. Richard Hatchett, of the Coalition for Epidemic Preparedness Innovations, told the Telegraph. “This is a scenario we have to prepare for. This is Disease X.”

The WHO coined the term Disease X in 2018.

One year later, as COVID-19 began to spread across China, the world witnessed a deadly pandemic caused by a new virus — a Disease X had emerged.

“It is not an exaggeration to say that there is potential of a Disease X event just around the corner,” Dr. Pranab Chatterjee, researcher at the Department of International Health at Johns Hopkins Bloomberg School of Public Health in Baltimore, told the National Post.

“The recent spate of H5N1 bird flu cases in Cambodia is just a case in point,” Chatterjee added.

Some public health experts believe the next Disease X will be zoonotic, meaning it will originate in wild or domestic animals, then spill over to infect humans.

Ebola, HIV/AIDS and COVID-19 were zoonotic outbreaks.

However, there are other sources of diseases and bioterrorism could be the cause of the next pandemic.

“The possibility of an engineered pandemic pathogen also cannot be ignored,” said the authors of a 2021 article in the journal Infection Control & Hospital Epidemiology.

“The release of such pathogens, either through laboratory accidents or as an act of bioterrorism, might lead to a disastrous Disease X as well and has been remarked as a global catastrophic risk,” the authors added.

Another possible source could be “zombie” viruses that have been locked in permafrost or other frozen landscapes for centuries, but are released by a warming climate.

The other priority diseases on the WHO list include Marburg virus, Crimean-Congo hemorrhagic fever, Lassa fever, Nipah and henipaviral diseases, Rift Valley fever and Middle East respiratory syndrome.

To prevent and combat an outbreak of Disease X, medical experts worldwide are clamoring for an increase in funds to support the surveillance of, and research into, potential pandemic agents.

“The COVID-19 pandemic was not the first to wreak havoc on the world and it will not be the last,” wrote the authors of the Infection Control & Hospital Epidemiology article. “Thus, we need to prepare for the next outbreak as soon as possible.”