Summary of an article published by BBC News Mundo on March 30, 2021
The most recent report from the World Health Organization (WHO) on the origin of the coronavirus leaves open one of the main unknowns of this pandemic: how the virus emerged and how it reached humans.
The investigation included a trip to China in late January for a mission in which a group of 17 Chinese experts worked alongside 17 international experts. During 14 days the experts visited hospitals, markets and laboratories; They also reviewed studies from other countries and analyzed samples taken from farms that supply markets in southern China.
However, the mission was strictly controlled by the local authorities, who initially resisted it being carried out.
4 conclusions about the origin of the virus
Based on the evidence collected, the experts concluded that:
1. It is “possible or probable” that the origin was a direct contagion from an animal to a human
According to the document, the animal that transmitted the virus directly to a human could be a bat, which are animals that are known to have a large proportion of viruses that can pass to humans. The report also leaves open the possibility that a pangolin or mink was the animal that infected a human with the virus.
2. It is “probable or very probable” that there was an intermediate animal between an infected animal and humans
This scenario suggests that a first animal that developed the virus infected an animal of another species and the latter infected a human. It is based on the fact that the viruses found in bats that are related to SARS-CoV-2 have certain differences that suggest that there may be a “missing link”. The document mentions that the growing number of animals that are susceptible to SARS-CoV-2 includes wild animals that are domesticated on farms.
3. It is “possible” that the virus has reached humans through food products
This hypothesis analyzed the possibility that the virus reached humans through food or the containers in which they are stored. This includes frozen foods that are commonly sold in markets such as Wuhan, however the WHO document maintains that there is no conclusive evidence of the transmission of SARS-CoV-2 from food and the likelihood of contamination of the cold chain with the virus is very low.
4. It is “extremely unlikely” that the virus reached humans due to an incident in a laboratory
The document clarifies that they did not analyze the possibility that someone had deliberately spread the virus. Nor did he inquire about whether the virus was manufactured in a laboratory, since this possibility has already been ruled out by other scientists based on the analysis of the virus genome. According to the WHO, the three Wuhan laboratories that work with coronavirus have “high-quality biosafety levels”, with a staff in which no diseases related to covid-19 were reported during the weeks or months before December 2019.
3 unanswered questions
The WHO document leaves several unknowns that can only be resolved with more research, including the animal farms that supply markets in Wuhan and other cities.
1. The Wuhan market
Many of the first reported COVID-19 cases are associated with the Huanan market, in the city of Wuhan. The investigation, however, maintains that “there is no firm conclusion” about the role that this place played in the origin of the pandemic. The document maintains that, although the first cases were related to the Huanan market, a similar number of cases were associated with other markets and others were not even related to a market.
The team confirmed that there was widespread SARS-CoV-2 contamination in the Huanan market in Wuhan, but could not determine the source of this contamination.
2. Farms in other countries
The research suggests that the virus could have reached the Wuhan market from wildlife farms that supply the market and where a higher prevalence of SARS-CoV-2 was detected in bats.
The document warns that, although this “does not demonstrate a link,” it opens up a significant avenue of investigation. When the first outbreak was detected, the Huanan market was receiving animal products from 20 countries, including some where positive cases of SARS-CoV-2 were reported in late 2019.
The study suggests that analyzing the trade in animals and products in other markets, as well as studying animals susceptible to the virus on farms in Southeast Asia, can provide clues to trace the origin of the virus.
3. First cases of contagion
The report also suggests that the SARS-CoV-2 virus could have been circulating for “several weeks” before it was first detected in humans. The team reviewed studies published in several countries that indicate an early circulation of the virus. The report says that several samples that appear to be positive were detected before the first case in Wuhan, suggesting that the virus may have been circulating in other countries.
Despite the advances in this investigation, the WHO director said that “finding the origin of the virus takes time.”
“A single research trip cannot provide all the answers,” he concluded.