World leaders are gathering to discuss Disease X. Here's what to know about the hypothetical pandemic.

World leaders gathered at the World Economic Forum's annual meeting in Davos, Switzerland, on Wednesday to discuss Disease X, a hypothetical virus 20 times deadlier than COVID-19.

While such a virus isn't known to currently exist, researchers, scientists and experts are hoping to proactively come up with a plan of action to combat such a virus and prepare the health system if it were to emerge as a pandemic — a possibility one expert told CBS News could happen sooner than we think.

"There are strains of viruses that have very high mortality rates that could develop the ability to transmit efficiently from human to human," said Dr. Amesh Adalja of the Johns Hopkins Center for Health Security.