" In 2013, the American virologist Ralph Baric approached Zhengli Shi at a meeting. Baric was a top expert in coronaviruses, with hundreds of papers to his credit, and Shi, along with her team at the Wuhan Institute of Virology, had been discovering them by the fistful in bat caves. In one sample of bat guano, Shi had detected the genome of a new virus, called SHC014, that was one of the two closest relatives to the original SARS virus, but her team had not been able to culture it in the lab.

Baric had developed a way around that problem—a technique for “reverse genetics” in coronaviruses. Not only did it allow him to bring an actual virus to life from its genetic code, but he could mix and match parts of multiple viruses. He wanted to take the “spike” gene from SHC014 and move it into a genetic copy of the SARS virus he already had in his lab. The spike molecule is what lets a coronavirus open a cell and get inside it. The resulting chimera would demonstrate whether the spike of SHC014 would attach to human cells."

..."The NIH decided the risk was worth it. In a potentially fateful decision, it funded work similar to Baric’s at the Wuhan Institute of Virology, which soon used its own reverse-genetics technology to make numerous coronavirus chimeras.

Unnoticed by most, however, was a key difference that significantly shifted the risk calculation. The Chinese work was carried out at biosafety level 2 (BSL-2), a much lower tier than Baric’s BSL-3+."...