Analysis of information sources in references of the Wikipedia article "Bệnh X" in Vietnamese language version.
By listing Disease X, an undetermined disease, the WHO is acknowledging that outbreaks do not always come from an identified source and that, as it admits, "a serious international epidemic could be caused by a pathogen currently unknown to cause human disease".
This hope now looks forlorn with the sudden emergence of the respiratory disease Covid-19, which has rapidly acquired most of the characteristic of a Disease X.
