They may not yet know its name but the next pathogen to cause a deadly global pandemic will most likely be a respiratory disease, spread by a virus that is contagious during incubation or when symptoms are only mild, according to researchers at the Johns Hopkins’ Center for Health Security.

They developed the outline as part of a framework to help scientists and policy makers prepare for the next emerging, catastrophic threat.

Their report, The Characteristics of Pandemic Pathogens, concludes that the culprit is less likely to be one of the headline-grabbing diseases that currently cause frightening outbreaks such as Ebola, carried in bodily fluids, or Zika, which is spread by mosquitoes.

Instead Disease X, as it has been dubbed by the World Health Organization, is most likely to be a virus that can spread through the air.