This is Alina Chan, one of the co-authors of Viral: The Search for the Origin of Covid-19.

I’m going to answer some of the questions that have come up in the comments.

1. Are Chan and Ridley selling a book?

Yes, the updated paperback comes out in the US next week: https://www.harpercollins.com/products/viral-matt-ridleyalin...

The updated epilogue now discusses three significant new developments since the publication of the hardback that are being hotly debated in the comments here. The first was the discovery of a virus in a bat in Laos that is slightly more similar to SARS-CoV-2 than the virus studied at the Wuhan Institute of Virology; but both are still not the progenitor of the pandemic. The second is detailed information about how prominent western virologists, who had privately thought the virus was likely manipulated in a laboratory, began to instead tell the public that no lab-based scenario was plausible. The third is a trio of conflicting studies about whether the Huanan seafood market was the site of a natural spillover of the virus from animals to people or just the site of a human superspreader event in December 2019.

As with the hardcover, half of our earnings from the book have gone/will go to charity.

2. Does the available evidence lean towards a market origin?

Some experts have asserted that there is dispositive evidence that the virus jumped from animals to people at the Wuhan Huanan market. However, their analysis failed to take into account the realities in the early days of the pandemic. Without access to the methodology and actual data collected by investigators in Wuhan, their interpretation unfortunately falls prey to ascertainment bias. Please see this thread for details: https://twitter.com/Ayjchan/status/1499794942012579843

At the moment, US intelligence, the WHO SAGO advisory group, and many top virologists and experts find both natural and lab origin hypotheses plausible and deserving of investigation. The evidence does not lean so strongly towards one hypothesis or the other that we can assume one as the default truth.

I personally think the available evidence points towards a lab origin but would not go as far as to say that there is dispositive evidence of it. Please see these 2 threads: https://twitter.com/Ayjchan/status/1524394197738049537 https://twitter.com/Ayjchan/status/1539745736807616513

3. Can scientists manipulate and genetically engineer naturally found viruses without leaving a trace? In other words, can the genome of the virus tell us its recent history?

We describe the seamless genetic engineering capabilities developed in the years leading up to the pandemic in VIRAL. Due to advanced technologies, it is no longer always possible to use the genome of a virus to distinguish between a natural pathogen vs one that has spent time in a laboratory. Even top coronavirologists, including Ralph Baric who collaborated with the Wuhan scientists, have said that the only way to know is to look at the Wuhan lab records. You can also read my twitter thread: https://twitter.com/Ayjchan/status/1493733086089121794

Even the presence of the furin cleavage site insertion that is unique to the pandemic virus and is indeed what makes it a highly infectious pandemic virus is not “dispositive evidence” of either a natural or lab origin. Please see our peer-reviewed analysis here:...