An argument for why the lab-leak theory of COVID’s origin remains unlikely

David Baltimore. Photo (cc) 2014 by Bob Paz.

Last week I wrote an analysis for GBH News on why the media dismissed the Wuhan lab-leak theory as the origin of COVID-19. I argued that the lab explanation got caught up in Donald Trump’s anti-Chinese racism and multifarious lies about the pandemic, compounded by some botched reporting of comments by Sen. Tom Cotton.

So I want to share with you two recent columns by Michael Hiltzik of the Los Angeles Times, someone whom I really respect. The Times has a tight paywall, but you should be able to access both of them by switching browsers after you read the first.

About a week ago Hiltzik examined the theory itself and concluded that, though it couldn’t be ruled out entirely, the scientific consensus remains that COVID almost certainly jumped from animals to humans outside the lab. He writes:

No one disputes that a lab leak is possible. Viruses have escaped from laboratories in the past, on occasion leading to human infection. But “zoonotic” transfers — that is, from animals to humans — are a much more common and well-documented pathway.

That’s why the virological community believes that it’s vastly more likely that COVID-19 spilled over from an animal host to humans.

Then, earlier this week, he reported that Nobel Prize-winning biologist David Baltimore was backing away from a quote he gave to former New York Times reporter Nicholas Wade in which he referred to genetic evidence that had been found as “the smoking gun for the origin of the virus.” Wade’s May 5 article in the Bulletin of the Atomic Scientists helped move the lab-leak theory to the center of the conversation. Hiltzik writes:

Baltimore told me by email that he made the statement to Wade, also by email, and granted him permission to use it in print. But he added that he “should have softened the phrase ‘smoking gun’ because I don’t believe that it proves the origin of the furin cleavage site but it does sound that way. I believe that the question of whether the sequence was put in naturally or by molecular manipulation is very hard to determine but I wouldn’t rule out either origin.” [Pardon me for not explaining “furin cleavage site,” but it’s related to the genetics of COVID.]

I think we have to regard both the lab-leak theory and animal-to-human transmission as possibilities, and we may never know the truth. But Hiltzik makes a powerful case that the animal-to-human explanation remains considerably more likely, and that it would be a mistake to regard the two explanations as equally plausible.