The first outbreak of the SARS-CoV-2 virus and the disease that would come to be known as Covid-19 occurred during the fall of 2019 in the Chinese city of Wuhan, but the world still doesn’t know the virus’s precise origin. Many scientists believe that the most likely explanation is zoonotic spillover, a process in which the virus jumped to humans through another species in the wild. Historical precedent makes the theory plausible—SARS-CoV-1, the virus that caused the 2002-04 SARS epidemic, seems to have crossed over from civet cats. But direct evidence that something similar happened in the case of Covid-19 has yet to emerge.
The alternative to the theory of zoonotic origin is, as science writer Nicholas Wade puts it, “the common-sense perception that a pandemic breaking out in Wuhan might have something to do with a Wuhan lab cooking up novel viruses of maximal danger in unsafe conditions.” In “Where COVID Came From,” Mr. Wade makes the case that Covid-19’s evolutionary history and anatomy, along with the Wuhan Institute of Virology’s research and safety record, suggests that the virus was modified by humans and escaped the lab.