Mr Rottingen explained Disease X could spark an epidemic if it was passed from animals to humans like HIV, which jumped from chimpanzees to humans claiming the lives of 35million people since the 1980s.
Advances in gene editing technology, which make the manipulation or creation of entirely new viruses possible, mean that Disease X could emerge through an accident or act of terror.
Despite its name, disease X is not spread around by one group of highly-gifted mutant children in both comic and film.
Disease X holds the potential to trigger a pandemic.
The most recent review took place in February, with experts agreeing that the following diseases are the ones that require the most attention from researchers: the Crimean-Congo haemorrhagic fever (CCHF), the Ebola virus and Marburg virus, the Lassa fever or Middle East respiratory syndrome coronavirus (MERS-CoV).
"History tells us that it is likely the next big outbreak will be something we have not seen before", John-Arne Rottingen, Research Council of Norway CEO and World Health Organization committee scientific adviser, told The Telegraph. He added that it may seem unusual to add a Disease X to the list.
"It may seem unusual to be adding an "X" but the point is to make sure we prepare and plan flexibility in terms of vaccines and diagnostic tests", the scientist explained, speaking to The Telegraph. The disease was believed to have started when a bat bit a toddler in Guinea. "We want to see "plug and play" platforms developed which will work for any, or a wide number of diseases; systems that will allow us to create countermeasures at speed", he added.
Where could a new deadly pathogen come from?
To that point, Rottingen pointed out in Dubai last month that as the world's ecosystems change and our habitats evolve, diseases in animals making the leap to humans is "probably the greatest risk". It also highlights diseases where there are now no cures of effective preventative measures. This has also brought us in closer contact and closer contact with more species of animals than ever before, exponentially increasing the likelihood of zoonoses.
A biological weapon is basically the deliberate utilization of contagious disease as a weapon.