Where did Covid-19 come from? The answer can be found in the SARS-CoV-2 virus itself. To get to the truth, we need only unleash the power of science. Based on experience with SARS-1 in 2003 and MERS in 2012, we know that many people are infected by a host animal long before a co-ronavirus mutates to the point where it can jump from human to human. An extensive data set from late 2019—more than 9,000 hospital samples—is available of people exhibiting flulike (thus Covid-like) symptoms in China’s Hubei and Shaanxi provinces before the epidemic started. Based on SARS-1 and MERS, the natural zoonotic theory predicts 100 to 400 Covid infections would be found in those samples. The lab-leak hypothesis, of course, predicts zero. If the novel coronavirus were engineered by scientists pursuing gain-of-function research, there would be no instances of community infection until it escaped from the laboratory. The World Health Organization investigation analysed those stored samples and found zero pre-pandemic infections. This is powerful evidence favouring the lab-leak theory.
Within months of the SARS-1 and MERS outbreaks, scientists found animals that had hosted the viruses before they made the jump to humans. More than 80% of the animals in affected markets were infected with a coro-navirus. In an influential March 2020 paper in Nature Medicine, Kristian Ander-sen and co-authors implied that a host animal for SARS-CoV-2 would soon be found. If the virus had been cooked up in a lab, of course, there would be no host animal to find.
The WHO team searched for a host in early 2020, testing more than 80,000 animals from 209 species, including wild, domesticated and market animals. Not a single animal infected with SARS-CoV-2 was found. This finding strongly favours the lab-leak theory. We can only wonder if the results would have been different if the animals tested had included the humanized mice kept at the Wuhan Institute of Virology.
In their Nature Medicine paper, Mr. Andersen and colleagues pointed to what they considered the poor design of SARS-CoV-2 as evidence of zoonotic origin. But a team of American scientists mutated the stem of the coronavirus genome in nearly 4,000 different ways and tested each variation. In the process they actually stumbled on the Delta variant.