Untangling the Theory About Covid-19 and a Wuhan Lab
A scientifically unsupported theory suggesting that Covid-19 accidentally escaped from a Wuhan laboratory gained undue credence when President Donald Trump addressed it in a press briefing last Friday. Asked whether the United States was investigating this theory, Trump said, “We’re looking at it; a lot of people are looking at it; it seems to make sense.”
Earlier this month, this idea was also addressed in a Washington Post opinion piece that flagged U.S. State Department cables warning of unsafe practices at the Wuhan Institute of Virology in 2018. Sen. Tom Cotton (R-Arkansas) further expounded on the idea in a commentary in the Wall Street Journal.
But the science does not support this speculation. Scientists are still not sure where exactly the SARS-CoV-2 virus that causes Covid-19 came from, but one thing is abundantly clear from the virus’s genes: The virus has a natural origin, most likely bats.
On March 17, a paper in the journal Nature laid out a genetic investigation of the origins of the virus. In the paper, the authors acknowledge that bat-derived coronaviruses are studied in labs around the world, and there are indeed documented cases in which the virus that causes SARS escaped. That’s part of the reason why they did the study. “We must therefore examine the possibility of an inadvertent laboratory release of SARS-CoV-2,” they wrote.
What they found in the genome of SARS-CoV-2 ruled out the possibility that it was ever manipulated in the lab. First, the section of the genome that encodes an important part of the virus’s spike protein — thought to be responsible for its potency — was not what they would have expected from human manipulation. Previous research had determined a specific genetic sequence that would optimize its potency, but the sequence they found in the actual virus didn’t match up. Rather than being designed in a lab, the unique sequence was “most likely the result of natural selection,” they wrote.
Secondly, they didn’t see any of the common signatures of genetic manipulation in the SARS-CoV-2 virus. Manipulating the genome of a virus would probably require a “reverse-genetic system,” they write, referring to a technique that involves tweaking an existing virus backbone or template. Their findings, however, “irrefutably show that SARS-CoV-2 is not derived from any previously used virus backbone.”
A letter published in The Lancet by an international team of scientists in February firmly established that the “virus originated in wildlife,” citing numerous genetic analyses from different countries. A perspective, published in the New England Journal of Medicine in April, points to bats as the likely origin.
This week, NPR spoke with 10 leading scientists who collect and study viruses, and all of them agreed that the virus transferred from animals to humans, much as the related coronaviruses SARS and MERS did, jumping from bats. They named the real threat as “zoonotic spillover” — when people pick up pathogens from wildlife.
In March, the United Nations’ biodiversity chief, Elizabeth Maruma Mrema, called for a global ban on wildlife markets for this reason. “The message we are getting is if we don’t take care of nature, it will take care of us,” she told The Guardian. On Tuesday, the BBC reported that the World Health Organization is working with the U.N. to create new guidelines for reopening wet markets.