Utilizing many circumstantial evidences and the use of statistics we can formulate an efficient statistical survey:
- Bats and other animals that harbor coronaviruses are found practically all over the world;
- Wuhan’s population is 11 million;
- The global population is 7 billion.
From these simple elements we can evaluate the possibility that just one person from Wuhan would have been patient zero: about 1 in 630. But we can amplify the survey. We now evaluate that in 2018 the WHO announced a discussion list of priority diseases pandemics, which included Ebola, Rift Valley Fever, and other viruses. In addition to these known diseases, WHO asked the experts to also name a currently unknown candidate. Drss. Shi Zheng-Li, director of the Wuhan Institute of Virology, proposed: <<Disease X could be a communicable infectious disease caused by a new coronavirus originating in bats>>. In other words, it did not more narrowly predict that the next pandemic would potentially be caused only by an alpha or betacoronavirus (the only ones known to infect humans were these 6: HCoV-NL63, HCoV-229E, MERS, SARS, HCoV-OC43 and HCoV-HKU1), not to mention the possibility that a possible new pandemic coronavirus would not emerge outside the pre-existing branches of the phylogenetic tree (such as MERS, a species totally unknown before starting to infect humans), but, coincidentally, SARS-CoV-2 emerges exactly among the species related to SARS, those that Drss. Shi Zheng-Li studied and manipulated extensively from 2005 to 2019 with 18 studies easily found by searching her publications online.
Considering that each species of Alpha and Betacoronavirus had exactly the same chance of spreading to humans, the odds of a virus specifically of the SARS-related coronavirus species starting a zoonotic pandemic was 1 in 28 (and since there are certainly many others coronavirus species to be discovered, the possibilities are actually even more slim). So, if we accept the above assumptions as reasonable, the odds that Wuhan would have been the site of a natural outbreak for a SARS-related coronavirus is obtained by multiplying 1 in 630 by 1 in 28. The result is 1 in 17,640, quite notable for not taking it into account.
Circumstantial evidences and statistics are a great support to understand the possibility that a laboratory leak happened, this should push for an indipendent international investigation.