According to the official website of the World Health Organization (WHO), WHO Director General Tedros recently issued a public warning about the possibility of an outbreak of "X disease", stating that the next pandemic outbreak is not a matter of whether it will occur, but of when it will occur, and calling for preparations to be made in response to "X disease". The unknown pathogen X disease has been mentioned multiple times recently. According to previous media reports, on January 17th local time, the World Economic Forum set up a sub forum titled "Preparing for X Disease", where the World Health Organization and representatives from multiple countries discussed how to deal with possible future "X Disease". Why does "X disease" alert the World Health Organization? Is its outbreak inevitable? What preparations can we make? What is "X disease"? In fact, "X disease" is not a specific disease that actually exists today. According to the World Health Organization, "X disease" refers to the possibility of an unknown pathogen causing a serious international pandemic. It has the opportunity to trigger from multiple sources at any time, and may take the lives of millions of people. This concept is not the first to be proposed. As early as 2018, the World Health Organization issued a similar warning, listing "X disease" as a "key pathogen" that could trigger epidemics or pandemics. Along with them are Ebola virus, Zika virus, and Severe Acute Respiratory Syndrome (SARS) virus. According to the official website of the World Health Organization, the inclusion of "X disease" is to cover unknown pathogens that may cause serious international epidemics. As for the original intention of putting forward the concept of "X disease", Zhao Wei, director of the Biosafety Research Center of the School of Public Health of Southern Medical University, pointed out in an interview with Zhongxin Health that the proposed concept is intended to avoid or reduce the harm of new or mutated pathogens, such as COVID-19, to human beings as far as possible. "In our lifetime, we may, and even very likely, face another pandemic. We don't know how severe it will be, but we can be prepared." Tan Desai recently said at the 2024 World Government Summit that despite some progress in monitoring, pandemic funding, vaccine production capacity, and other areas, the world is still not ready for the next "X disease" and the next pandemic based on the current situation. Will "X disease" definitely come? Tan Desai stated at the aforementioned conference that the next outbreak of a pandemic is not a matter of whether it will occur, but of when it will occur. "Viruses in nature constantly threaten human health. Although more than 300 kinds of viruses that can infect humans have been found, there are still a large number of unknown viruses to be confirmed, many of which may have the ability to break through barriers between species and infect people." Lu Hongzhou, director of the National infectious diseases Clinical Medical Research Center and president of Shenzhen Third People's Hospital, told China New Health that a study showed that among the 25 virus families investigated, there are about 1.67 million unknown viruses to be found, 631000 to 827000 of which may infect people. Lu Hongzhou pointed out that with the increasing frequency of international exchanges, new pathogenic microorganisms are accelerating their emergence, and the prevention of large-scale infectious diseases is becoming increasingly difficult. Previously, he mentioned in an interview that