Friday, April 3, 2020

COVID-19 conspiracy theories: Hoofbeats and zebras?

Lots of conspiracy theories about the new coronavirus make little sense, and if you actually apply a little scientific rigor to the issue, they fall apart.

They even contradict each other. If it came from a Chinese lab, why? They got hit first. If, as some
Russians say, it came from America, why are we Americans also sick? Whoa, what about the fact that
Russia seemed to be largely free of the disease, isnʻt that suspicious? Well itʻs not, any more--they've got a growing number of cases as well.

The philosopical theory known as Occamʻs Razor suggests that the simplest solution is generally the
right one. There's the old line that if you're in the American west and hear hoofbeats, your first thought should not be zebras.

A group of researchers looked into whatʻs likely and whatʻs not about the origins of COVID-19, also
known as SARS-CoV-2.

1. They found that we know of seven previous cases of this class of disease getting into humans;
2. They found that itʻs highly unlikely that this was a human-engineered virus.

Their study was published in the journal Nature Medicine. The authors are American, Australian and British researchers Kristian G. Andersen, Andrew Rambaut, W.vIan Lipkin, Edward C. Holmes and Robert F. Garry.

"Our analyses clearly show that SARS-CoV-2 is not a laboratory construct or a purposefully manipulated," they wrote.

One clue, they said, is that when you look at the genetics, this virus behaves more like a random
mutation than a purposeful construct. In other wordS, if someone had engineered it, theyʻd have done a better job, or at least would have done it differently.

Which is not to say that labs donʻt work on viruses. They do. But not like this. "The genetic data irrefutably show that SARS-CoV-2 is not derived from any previously used virus backbone," the authors wrote.

The most likely pathway is one of two, Anderson and his co-authors said. Either the virus evolved into its current form in an animal and then was passed to humans, or an earlier form of the virus passed from animals to humans and then evolved into its current form in humans.

You may have heard that many of the early victims of the virus had visited live-animal markets in
Wuhan, China. And that the animal host might have been bats, or pangolins or birds.

So far, none of those animals has been found with a form of the virus that looks close enough to be the source of the COVID-19 pandemic, they said, but they admitted that the animal population has been "massively undersampled." Pangolins seem to have the virus version closest to the pandemic version.

Alternatively, it is possible an early version of the virus jumped repeatedly to humans in a version that did not spread from human to human. Until one evolved the ability to be transmitted between people.

It is not yet possible to determine which of these things actually led to the outbreak, but there is lots of study going on, and at some point, it will be possible.

"We do not believe that any type of laboratory-based scenario is plausible," but more research will doubtless show which of the natural mechanisms was the more likely culprit.

One of the best arguments against a laboratory conspiracy to infect the world: Animal-to-human transfer of disease has been a common source of human misery since long before sophisticated laboratories were set up. There is even a term for it, zoonosis. That link is the Centers for Disease Control site on zoonotic diseases.

We have had lots of zoonotic diseases in Hawai`i, like leptospirosis and dengue, but most of these diseases require an animal-to-human infection path for each sick human. The difference with COVID-19 is that once it crossed the species barrier, it could be transmitted directly human to human.

This has happened repeatedly. Think of bird flu and swine flu. The source of the devastating 1918 "Spanish" flu, is not well known, although it almost certainly didn't come from Spain. It went on to infect a third of the world population and to kill an estimated 50 million people. Some suggest it might have crossed from birds.

Thus, this is neither new nor rare. "More than 60% of the roughly 400 emerging infectious diseases that have been identified since 1940 are zoonotic," wrote the authors of this 2012 paper in the journal The Lancet, which has the ominous title, "Prediction and prevention of the next pandemic zoonosis."

© Jan TenBruggencate 2020

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