Did the virus that causes Covid-19 escape from a laboratory?

generated scepticism. Alina Chan and Matt Ridley argue that an accidental laboratory leak from the nearby Wuhan Institute of Virology, where researchers had been “exploring caves in search of bats that harbour Sars-like viruses and isolating genetic material from their saliva, urine and faeces”, is a more likely explanation.

The book collates “circumstantial but damning” evidence that supports the laboratory-leak theory, says Tom Chivers in The Times. The Chinese team at Wuhan sequenced a very similar bat virus in 2012. Unlike with Sars, “extensive testing” in Wuhan has failed to uncover an animal host. Other pieces of evidence pointing toward a leak include the bug’s apparently slow evolution, unusual in animal viruses, and the fact that it has a “furin cleavage site”, unknown in normal coronaviruses, making it uniquely infectious. The questions the authors raise “need to be answered more fully”.

Perhaps, but they won’t be, says Steven Poole in The Daily Telegraph. The authors provide plenty of evidence that a laboratory leak was “possible”, but no direct evidence that it actually occurred, and as China “isn’t interested in helping”, they are unlikely to find any in the future, even if it exists. Still, regardless of the details of this case, they make a strong argument for closer regulation of “gain-offunction research”, in which viruses are manipulated to become more dangerous. At the very least, research institutes “should be a lot more circumspect about when and how they do it”.