Definition

A hypothetical (future and unknown) disease that could cause a pandemic. Disease X could be a zoonosis.

Further reading
Preparing for Disease X in a Changing World - The Scientist (Bradford, 2025) [website]
DISEASE X - What it is, and what it is not - Coalition for Epidemic Preparedness Innovations (CEPI) [website]
Related

blueprint priority diseases; Disease X placeholder; infectious diseases; new infection; pandemic preparedness; Pathogen X; spillover events; spillover infections; unknown pathogen; vaccinations; vaccines

See also
One Health
Pandemic
Zoonosis
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Drafted by
Chris Graham
Reviewed by
TBC