High-Priority Pathogens with Potential to Cause “Disease X” Pandemics

In past decades, numerous emerging infectious diseases have markedly affected global health and social-economic development. Consequently, the concept of “disease X” has been developed, and lists of the pathogens with potential to cause future pandemics have been proposed and updated several times by the World Health Organization. Herein, we analyzed the major features of pathogens with high probability to cause future COVID-19-like pandemics, on the basis of their transmission routes, animal-human interfaces, herd immunity barriers, and evolutionary and mutational characteristics. We also evaluated high-priority viral infectious diseases with potential to become disease X in the future, on the basis of their transmission pathways, including airborne/respiratory, vector-borne, and direct contact. Overall, viruses had much greater likelihood of becoming “pathogen X” than either bacteria or other microorganisms. Respiratory viruses, particularly RNA viruses, have notably high potential to become pathogen X. Vector-borne viruses might also become pathogen X, and mosquito-borne viruses would be more likely than tick-borne viruses to do so. Many contagious viral infectious diseases lead to severe clinical outcomes but have relatively low likelihood of causing global pandemics. Coronaviruses in the Coronaviridae and influenza viruses in the Orthomyxoviridae were identified as top-priority pathogens X with potential to cause the next COVID pandemic.