Thursday, March 2, 2023

And Moar Yellow Peril


Via Wikipedia.

The other thing I wanted to say about the lab leak hypothesis goes more or less like this: 

We don't know anything with "high confidence" about whether the SARS-CoV-2 originated in a laboratory or not, but we do know with a good deal of certainty that if it did, it's the first pandemic virus to have originated that way.

While there is quite a long history of pandemics and epidemics that got started with what's called a zoonotic transfer of some infectious agent, virus or bacteria or fungus or parasite, to a human population: Ebola and HIV, bird flu and swine flu, measles and smallpox, hantoviruses and cold-causing coronaviruses, not to mention SARS-CoV-1 and MERS and RSV, and of course bubonic plague, the king of them all. 

Of course it's also true that the kind of research the lab leak partisans are most interested in hinting at, in which scientists might have, say, taken some coronavirus found in bats and purposely made it more capable of jumping to humans, has only been possible in the last ten or twelve years in the advent of the CRISPR technique, so it wouldn't have happened very often, at least not yet. On the other hand, however, the other scenario, of a virus or other pathogen leaping from its normal animal host to a human, happens literally all the time. Most pathogens new to the human race are the results of such a spillover. While scientists believed for a long time that the spillover event is pretty rare, I learned from a recent NPR report that it actually isn't rare at all; it just usually isn't possible to say how it happened:

When a person comes to a hospital with a severe respiratory infection, it doesn't matter whether they're in Sarawak, Malaysia, or San Francisco, Calif. Doctors run tests to see what's causing the infection. But this panel of tests identifies the source of an infection only about 40% of the time, says virologist John Lednicky at the University of Florida. "I like to think about it as 60% of the time doctors have absolutely no idea what is causing the respiratory illness."

So a recent research trend has been to focus on that 60%, looking for the pathogens in those mystery cases; rather than the cataloguing of the million-plus animal viruses that exist, the vast majority of which will be incapable of spilling over into humans, as is done in labs around the world like the one in Wuhan, to give the most attention to the ones that have proven they can, testing with instruments more sensitive than the standard panel that can identify maybe half a dozen well-studied viruses, to look for the pathogens already infecting humans of whose existence you weren't aware. Because it's from among those, or pathogens that resemble them, that the next epidemic is likely to arise:

Most human infectious diseases (60-75%) are derived from pathogens that originally circulated in non-human animal species. This demonstrates that spillover has a fundamental role in the emergence of new human infectious diseases. Understanding the factors that facilitate the transmission of pathogens from wild animals to humans is essential to establish strategies focused on the reduction of the frequency of spillover events....

The emergence of a new human disease and its dissemination in the population occurs only when biological, social, and environmental conditions are favorable for the replication/adaptation of the pathogen in the human host and its transmission among the new population [but, a]lthough spillover events that result in new human diseases are not common, when they do occur, the impacts can be very important, either by the appearance of a new human disease, or by the spread of the new disease on a large scale.

The trouble with getting all excited over the lab leak hypothesis is that it's so extremely improbable; even if it happens to be true in this case, it's going to inspire the wrong kind of research, into Dr. Moreau fantasies and anti-Chinese paranoia (the respectable lab leak proponents are talking about an accident, but the crazies see a bioweapons program meant to wipe us all out)—it pushes a preoccupation with the least likely worry. 

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