Nearly two years after the COVID-19 pandemic, the origin of the virus that tormented the world is still shrouded in mystery.

Most scientists believe that it appeared in the wild, jumping directly from bats or through other animals to humans. Others think it escaped from a Chinese laboratory.

Now, on the second anniversary of the first human case, the global death toll from COVID-19 exceeds 5.2 million, and more and more scientists are trying to focus on what they consider to be more reasonable “zoon diseases” or animal pairs- Humans, theories, hope that what they have learned can help humans resist new viruses and variants.

University of Utah scientist Stephen Goldstein (Stephen Goldstein) wrote an article with 20 other people. He said: “The leak in the laboratory has caused a lot of attention in places such as Twitter”, but “there is no evidence of this virus. Exist in the laboratory” in the August issue of Cell, listed the evidence of animal origin.

University of Arizona evolutionary biologist Michael Vorobbie, who contributed to this article, signed a letter with other scientists last spring stating that both theories are feasible. He said that since then, his own and other studies have made him more confident in the animal hypothesis than before, “just supported by more data.”

Last month, Worobey published a COVID-19 timeline linking the first known human case to the South China Seafood Wholesale Market in Wuhan, China, where live animals are sold.

“The idea of ??a leak in the laboratory is almost certainly a huge distraction. It diverts attention from what is actually happening,” he said.

Others are not so sure. This summer, a review ordered by President Joe Biden revealed that four U.S. intelligence agencies believed that the virus was originally transmitted from animals to humans with low confidence, and one agency believed that the first infection was related to the laboratory with moderate confidence. related. .

Some proponents of the laboratory leakage hypothesis believe that researchers were accidentally exposed due to inadequate safety measures when handling samples in the field, or possibly after creating a virus in the laboratory. US intelligence officials denied China’s suspicion of developing the virus as a biological weapon.

The constant search for answers has exacerbated tensions between the United States and China, which accused the United States of using it as a scapegoat for disaster. Some experts worry that the origin of the pandemic may never be known.

From bat to man

Scientists stated in the Cell paper that SARS-CoV-2, which causes COVID-19, is the 9th documented coronavirus that infects humans. Everything in the past originated from animals.

This includes the virus that caused the SARS epidemic in 2003, which is also related to the market for the sale of live animals in China.

Many researchers believe that wild animals are intermediate hosts of SARS-CoV-2, which means that they were infected with bat coronavirus and then evolved. Scientists have been searching for the exact bat coronavirus involved, and in September found three viruses in bats in Laos, which are more similar to SARS-CoV-2 than any known virus.

Worobey suspects that the raccoon dog is the intermediate host. He said that this fox-like mammal is susceptible to coronavirus and is sold alive in the South China market.

Goldstein said that the “gold standard evidence of animal origin” will be infected animals from there. “But as far as we know, the market has cleared.”

Earlier this year, a joint report by the World Health Organization and China stated that the spread of the virus from bats to humans through another animal is the most likely scenario, and laboratory leaks are “very unlikely.”

But the report also aroused suspicion, because he designated the first known COVID-19 case as an accountant who had no connection with the South China market and had symptoms for the first time on December 8, 2019. Worobey said supporters of the laboratory leak theory pointed to the case claiming that the virus escaped from the Wuhan Institute of Virology facility near the man’s residence.

However, according to Worobey’s research, the man said in an interview that his illness on December 8 was actually a dental problem, and his COVID-19 symptoms began on December 16, which was confirmed in hospital records .

Worobey’s analysis identified an earlier case: a supplier in the South China market was infected with COVID-19 on December 11.

Animal threat

Experts worry that the spread of the same virus from animals to humans may trigger a new epidemic — and make this epidemic worse.

Since the emergence of COVID-19, many types of animals have been infected, including pet cats, dogs, and ferrets; zoo animals such as big cats, otters, and non-human primates; farmed minks; and white-tailed deer.

According to the US Centers for Disease Control and Prevention, most people get the virus from humans. The center stated that humans can transmit the virus to animals during close contact, but the risk of animals transmitting the virus to humans is very low.

However, another concern is that animals may release new variants of the virus. Some people wonder if the omicron variant started this way.

David O’Connor, a virology expert at the University of Wisconsin-Madison, said: “Around the world, even if we control (COVID-19) on humans, we may allow animals to incubate these variants.” “We may not be in the short term. A large-scale giraffe immunization program is carried out within.”

Worobey said that he has been looking for genetic fingerprints that might indicate whether omicron was produced when the virus spread from humans to animals, mutated, and then jumped back to humans.

Experts say that preventing zoonotic diseases requires not only combating the illegal sale of wild animals, but also progress on major global issues that increase the risk of human-animal contact, such as habitat destruction and climate change.

Scientists stated in the Cell paper that failure to fully investigate the animal origin of the virus will “make the world vulnerable to future pandemics. These pandemics are caused by the same human activities. These human activities have repeatedly caused us to The new virus is in conflict.”

“Toxic” politics

But further investigation was hindered by superpower politics. Lawrence Gostin of Georgetown University said that there was a “naked battle” between China and the United States.

Gostin, director of the WHO National and Global Health Law Cooperation Center, said: “The politics surrounding the origin investigation actually poisons the wells of global cooperation.” “Politics is actually poisonous.”

An Associated Press survey last year found that the Chinese government strictly controls all research on the origin of COVID-19 and promotes the marginal theory that the virus may come from abroad.

“This is a very closed country instinctively, and it will never allow foreigners to enter its territory without restrictions,” Godin said.

However, Godin said that the investigation has made a positive progress.

The WHO established an advisory group to investigate the origin of the pandemic. Gostin said that although he doubts the team can solve the mystery, “they will have a group of highly qualified scientists ready to deploy immediately in the next pandemic.”