Dr. Tedros Adhanom Ghebreyesus, the Director-General of the World Health Organization, referred to Covid as “our first Disease X” at the World Economic Forum in Davos. Disease X denotes a contagious disease of which nothing is known at the time of its emergence, including the pathogen, transmission routes, and affected hosts. The focus in research is on identifying the virus with the highest pandemic potential, with historical evidence pointing to influenza viruses as the primary candidates for causing pandemics. The history of the 20th century witnessed three influenza pandemics: the Spanish flu (H1N1, 1917-1919), Asian flu (H2N2, 1957), and Hong Kong flu (H3N2, 1968), all of which acquired genes from animal viruses.
Initially, coronaviruses were considered less likely to cause a pandemic, but the outbreak of the Sars 1 virus in 2002 and the MERS virus in 2012 challenged this perception. These coronaviruses demonstrated low transmissibility and high virulence, leading experts to consider them less of a pandemic risk. However, the emergence of Covid-19 served as a humbling lesson, highlighting the need for preparedness and caution. In conclusion, the Covid-19 pandemic has led to a reevaluation of the perceived risks posed by coronaviruses in light of their potential for causing global health crises.