Leak of the coronavirus from a laboratory: an unlikely and speculative theory, but possible | Society

If there was a trial to judge the origin of the coronavirus, innocence would amount to spontaneous transmission to humans: it would be the sentence if the opposite was not proven. Very strong evidence would be needed to conclude that the virus infected a person in a laboratory and that is where transmission started; today there is none. The problem is that the the murder weapon, the intermediate animal that transmitted a virus from a bat to a person and started the whole chain of infections until it started a pandemic. And until it is found, the door to other hypotheses cannot be completely closed.

A letter published in the magazine Science on May 14 by 18 prestigious scientists (including a single coronavirus expert) asking that the hypothesis of an escape from the laboratory not be ruled out reopened the discussion. Joe Biden, President of the United States, rose to the challenge and requested a conclusive report in 90 days, which, on the other hand, is extremely complicated.

Beyond that, the letter and the presidential ruling, there is no new strong evidence to suggest that the majority thesis of the scientific community, transmission through an animal intermediary, is incorrect. But it shows this alternative slot that is arousing great interest: Theories of natural selection find it hard to compete with the mystery.

In this case, moreover, it is not an irrational conspiracy, such as the one which guarantees that the Earth is flat. There is reason to believe the leap to humans could have happened in a lab: not that it was created there, which is in keeping with the most unlikely conspiracy theories. What has gained in strength is that the first human infection was the product of an accident in an experiment. “The odds are low but not minimal, and it is important to conduct a credible and comprehensive investigation into the origin of the pandemic which includes the possibility of a laboratory accident”, Stephen Goldstein, expert virologist in coronavirus at the University from Utah. “However, prioritizing this hypothesis at the expense of studying the conventional zoonotic route would be a huge mistake,” he says.

It is difficult to make an exclusively scientific analysis of the situation and to escape the geopolitical implications of the debate. An opaque system like the Chinese does not make it easy to find the answer and all of this is happening between the rivalry between Washington and Beijing. These are the arguments for and against the two hypotheses.

The spontaneous transmission hypothesis

As SCCI virologist Isabel Sola explains, this is the most plausible because it is a known phenomenon, which has already happened before in a place also plagued by coronaviruses that can make the jump to humans. So much so that high levels of antibodies against SARS-like coronaviruses have been found in animal traders in southern China’s Canton province. An outbreak of this pathogen in 2003 was the most direct antecedent of the one that causes covid. Another similar was the MERS, six years later. The difference is that then the intermediate host has been found: the civet in the first case and the dromedary in the second.

The main suspect at the start of the pandemic is the bat, which harbors a virus (called RaTG13) that has an affinity of over 96% with SARS-CoV-2, which is responsible for covid-19. “The normal evolution time for this virus to become capable of infecting humans is about 20 years. When an intermediary animal intervenes, it accelerates the evolution of the virus and a much more similar animal could be generated. But since we don’t have that connection, we can’t say 100% that it happened, ”says Sola.

An additional difficulty in finding this link is the frequency of asymptomatic disease. Unlike the first SARS, which quickly showed severe effects, COVID began to spread much more silently, making it much more difficult, if not impossible, to reach patient zero.

With these bases, a scientific commission of the World Health Organization (WHO) which investigated in the field could not find the intermediate host, but indicated this option as “probable or very probable”, whereas that of jumping to humans in the lab was almost written off as “extremely unlikely”. Autonomous University of Madrid virologist José Antonio López Guerrero points out that this conclusion seems more reliable than a letter in Science this is not supported by any evidence: it is actually five paragraphs requiring further research. “What the research shows is that it appeared at the same time in different markets in different cities,” he explains. This is wrong when you leave the lab.

The theory of laboratory escape

“Although the team concluded that the laboratory leak is the least likely hypothesis, it requires further investigation, possibly with other missions,” said Tedros Adhanom Gebreyesus, director of WHO, during the publication of the report which designated the intermediate host as the most option. likely.

The biggest endorsement for the lab breakout thesis is that the other has not been proven. “We know the bat virus and humans: what do we put in between? As long as we don’t find it in an animal, we can say that someone handled it in a laboratory and that it escaped, even if we have no proof, ”explains Sola.

Miguel Ángel Martínez-González, professor of public health at the University of Navarre, addresses these two hypotheses in his book Health on fire: an internist and an epidemiologist facing the pandemic, which will go on sale in June. Although he insists on maintaining the “presumption of innocence”, he exposes some of the factors which may lead to the belief that the first infection of the virus occurred in a laboratory and from there it spread. .

First of all, Wuhan has a center where people are suffering from coronavirus. This is a first indication that, although it is not sufficient, it is necessary to support this thesis. Behind this there are several unclear phenomena that support the theory. The last Sunday, The Wall Street Journal published an article citing anonymous intelligence sources who claim that three researchers from that lab were admitted to a hospital with pneumonia in November. “The clinical history of these researchers is not available, but it would be very rare for this to coincide with pneumonia when the virus is thought to have started circulating,” explains Martínez-González.

While it is confirmed that three scientists have been infected with SARS-CoV-2, which China has denied, López Guerrero acknowledges that the the laboratory hypothesis would gain ground. “Surely it would continue to be a natural infection, but instead of a market, it would have happened there,” he says.

But there are those who go further and claim that not only did an infection occur in a lab, but it was the scientists who developed the mutations necessary to become a human pathogen. Like all of the above, it is based on evidence and speculation, not evidence.

The lab had been experimenting with the coronavirus for years. Zhengli-Li Shi, says the bat doctor, collected a thousand samples of the coronavirus from bats to investigate. As Martínez-González explains, the Wuhan Institute published in Nature medicine of 2015 which modified one of these viruses to make it more infectious. “This publication elicited reactions like that of Wain-Hobson, of the Pasteur Institute, who then asked for caution, because if this virus escaped, no one could predict its trajectory,” he said. Additionally, according to a 2018 report from the U.S. National Institutes of Health, security in these labs was not required for this type of testing. These experiments, Sola says, were viruses attenuated so they could not be infectious in humans in a real setting, according to their own publications.

According to Nerea Irigoyen, a virologist at the University of Cambridge, “it is likely that we will never know the origin of the virus”. Because? “Because there is most likely an intermediate animal that can be anywhere in Southeast Asia and it can take years to find it, if it can be found.”