The WHO warned: “Disease X represents the knowledge that a serious international epidemic could be caused by a pathogen currently unknown to cause human disease.” Disease X could spark an epidemic if it was passed from animals to humans like HIV. Norwegian scientist and WHO adviser John-Arne Rottingen said that it was likely the next outbreak would be “something we have not seen before”. Disease X could even be man-made, rather than a fluke of nature. There are growing fears that the use and development of chemical and biological weapons are on the rise.
Tom Frieden, a former leading disease control director in the US, said: “We don’t know where the next threat will come from. But we are certain there will be a next time.” In previous years the list of WHO has been confined to known killers such as Lassa fever, which is currently sweeping Nigeria, and Ebola, which killed more than 11,000 people in an epidemic in West Africa between 2013 and 2016. WHO hopes that formally designating “Disease X” as the unknown next pandemic will help spur researchers worldwide into preparing a rapid response to any surprise outbreak.