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.