We still don’t know the origin of the virus that has killed hundreds of millions of people worldwide. Two years ago, the consensus was that it was a zoonotic virus that jumped from an animal species to humans, or perhaps jumped through an intermediary at the wet market in Wuhan, China.

There were a few reasons then, and many reasons now to doubt that scenario. There was only one laboratory in China able to handle such coronaviruses, and that was the Wuhan Institute of Virology. It seemed like quite a coincidence that the outbreak took place there. Also, there weren’t any animals tested that had this virus or anything like it.

But we now have even more biological evidence. Matt Ridley and Alina Chan are the authors of Viral: The Search for the Origin of Covid-19. They provide plenty of circumstantial evidence for a lab leak, and they also answer the question of why finding the origin of virus is so important.

The Wuhan Institute of Virology was the center of a global effect to catalogue viruses with pandemic potential. We also know that scientists there were engage in gain-of-function research. Even more important is the fact that this virus has a unique 12-letter genetic sequence (the furin cleavage site) that is not seen in other coronaviruses that also makes it much more infectious.

They also explain why it is so important to find the origin of this virus. If it came from animals in the wild, we need to identify which species carries this virus. If it was produced from some farming practice, we need to stop that practice. And if it came from a laboratory, we need new safety and regulatory procedures.

We need to know the origin of this pandemic, or we are likely to experience another one in the future.