Lab-Leak Theory: Kristian Andersen On His Fauci Email and Covid Origins - The New York Times

Fauci, the government’s top infectious disease expert, that some features of the virus made him wonder whether it had been engineered, and noted that he and his colleagues were planning to investigate further by analyzing the virus’s genome.

At the time, based on limited data and preliminary analyses, we observed features that appeared to potentially be unique to SARS-CoV-2.

We had not yet seen these features in other related viruses from natural sources, and thus were exploring whether they had been engineered into the virus.

Those features included a structure known as the furin cleavage site that allows the SARS-CoV-2 spike protein to be cleaved by furin, an enzyme found in human cells, and another structure, known as the receptor binding domain, that allowed the virus to anchor to the outside of human cells via a cell-surface protein known as ACE2.

Many of these analyses were completed in a matter of days, while we worked around the clock, which allowed us to reject our preliminary hypothesis that SARS-CoV-2 might have been engineered, while other “lab”-based scenarios were still on the table.

For example, we looked at data from coronaviruses found in other species, such as bats and pangolins, which demonstrated that the features that first appeared unique to SARS-CoV-2 were in fact found in other, related viruses.

Overall, this is a textbook example of the scientific method where a preliminary hypothesis is rejected in favor of a competing hypothesis after more data become available and analyses are completed.

As we stated in our article last March, it is currently impossible to prove or disprove specific hypotheses of SARS-CoV-2 origin.

However, while both lab and natural scenarios are possible, they are not equally likely — precedence, data and other evidence strongly favor natural emergence as a highly likely scientific theory for the emergence of SARS-CoV-2, while the lab leak remains a speculative hypothesis based on conjecture.

In contrast, the scientific theory about the natural emergence of SARS-CoV-2 presents a far simpler and more likely scenario.

I have always supported further inquiries into the origin of SARS-CoV-2, including President Biden’s recent call, as it is important that we more fully understand how the virus emerged.

Other evidence, were it to emerge, could lend further weight to the natural origin hypothesis.