But none far come light.According WHO report origins virus , sentinel hospitals Hubei province , home Wuhan , routinely monitor influenza-like illnesses “ evidence suggest substantial SARSCoV-2 transmission months preceding outbreak December observed. ” So ’ hard explain SARS2 virus picked furin cleavage site naturally , whether mutation recombination.That leaves gain-of-function experiment.For think SARS2 may escaped lab , explaining furin cleavage site problem all. “ Since 1992 virology community known one sure way make virus deadlier give furin cleavage site S1/S2 junction laboratory , ” writes Steven Quay , biotech entrepreneur interested origins SARS2. “ At least 11 gain-of-function experiments , adding furin site make virus infective , published open literature , including [ ] Dr. Zhengli Shi , head coronavirus research Wuhan Institute Virology. ” 4 ) A question codons .