It is not a 'specific disease' but is the name given to a potential novel infectious agent.
It could pose a serious microbial threat to humans in the future.
With no vaccines or treatments, Disease X could give rise to a severe epidemic.
According to scientists, COVID-19 marked the first instance of Disease X.
WHO added Disease X to priority research list alongside SARS and Ebola.
Next pandemic caused by Disease X is feared to be deadlier than all others so far.
Researchers think it could be as devastating as Spanish Flu of 1918-1920 and kill over 50 million.
Disease X could result in 20 times more fatalities than COVID-19.
WHO has already started implementing measures to prepare for another outbreak.
Disease X is being discussed at ongoing World Economic Forum in Davos, Switzerland.