The World Health Organisation uses the term "disease X" to refer to a potential future illness that might spark a worldwide pandemic. A term coined in 2017, it is a catch-all for any unidentified pathogen with potential for epidemics. The WHO recently emphasised the necessity of having everyone on the planet prepared for this kind of illness. There are several potential sources of disease X, such as coronaviruses or other recognised pathogens like Zika, Ebola, or bird flu. To counter this possible threat, improvements in healthcare systems and vaccine technology, particularly mRNA vaccines, are essential.