Disease X is a placeholder term that was used by the World Health Organization (WHO) in February 2018 for their shortlist of high priority illnesses to symbolize a hypothetical, unidentified pathogen that might create an epidemic in the future. The WHO used the placeholder term so that their planning would be adequately adaptable to an unidentified virus (e.g., broader vaccines and manufacturing facilities).
Anthony Fauci, director of the US National Institute of Allergy and Infectious Diseases, stated that Disease X would encourage WHO projects to focus their research efforts on entire classes of viruses (e.g., flaviviruses), rather than just individual strains (e.g., zika virus), thereby enhancing WHO’s ability to respond to unexpected strains. In 2020, it was believed, including by some of the WHO’s own expert advisors, that COVID-19, which was caused by the SARS-CoV-2 viral strain, fit the criteria to be the first Disease X.
Major Facts
- “The X in “Disease X” represents all the unknowns.
- This is a new illness about which we will know nothing when it first appears; it may or may not be fatal, extremely contagious, and a menace to our way of life.
- We also don’t know when or how it will come across the viral frontier and infect people.
- However, we are aware that Disease X may reappear, and we must be prepared.
Prioritized research list of emerging illnesses compiled by the World Health Organization:
A WHO tool distinguishes which diseases pose the greatest public health risk due to their epidemic potential and/or whether there are no or insufficient countermeasures.
At present, the priority diseases are:
- COVID-19
- Hemorrhagic fever of Crimea and Congo
- Ebola virus illness and Marburg virus disease
- Lassa fever
- Coronavirus that causes Middle East respiratory syndrome (MERS-CoV) and severe acute respiratory syndrome (SARS)
- Nipah and henipavirus infections
- Rift Valley fever
- Zika
- Disease X
What could be the next pandemic?
New viruses (especially novel coronaviruses) may pose a danger to world health, but scientists have found a number of existing infections that might cause massive epidemics.
The great majority of them are viruses, particularly hemorrhagic fever viruses (including Ebola, hantavirus, and Lassa fever), flaviviruses (dengue, zika, and yellow fever), and coronaviruses (MERS, and new strands of COVID).
Pathogens that might produce pandemics due to their drug resistance, such as TB and staphylococcus, are currently prevalent in many regions of the world.
Future pandemics may be triggered by bioterrorism with agents such as anthrax or smallpox.
