Following an on-site investigation of the first detected outbreak, the WHO maintains the zoonotic explanation for COVID-19, although it will also investigate a possible origin in the food cold chain.
Editorial Staff/EFEMar
As expected, the investigations to solve the origin of the coronavirus that has all of humanity in check have not been resolved in a matter of days (infectious disease specialist Dominic Dwyer already said that it will probably take years to understand the origin of covid-19).
The team of scientists from the World Health Organization (WHO) who traveled to Wuhan, China, where the first cases of COVID-19 were reported, presented the results of their investigations at a lengthy press conference on Tuesday. This group of experts arrived in Wuhan on January 14 and, after the required two-week quarantine, gathered information from the Huanan Seafood Market, where the first known cases were recorded, as well as from the Wuhan Institute of Virology, where scientific teams were researching coronaviruses.
According to researchers, there is new information, but nothing that overturns current theories about the emergence of SARS-CoV-2: bats as a reservoir for the virus is currently the strongest suspicion, although it appears that the animals were not necessarily in Wuhan. The hypothesis that the virus escaped (accidentally or through a conspiracy) from a laboratory, including the Wuhan Institute of Virology, is practically ruled out.
However, it is likely that the virus passed through an intermediate animal from its natural reservoir before beginning to spread between humans. WHO researchers have also opened the door to other sources, such as frozen food, a line of research pursued by Chinese experts who have repeatedly reported finding traces of coronavirus on imported food packaging. Regarding this latter hypothesis, WHO experts clarify that, while it is known that the virus can survive cold and frozen environments, it has not been confirmed that it can be transmitted from this source to humans.
The head of the WHO's international expert mission, Danish zoonosis specialist Peter Ben Embarek, stated at the press conference that "everything continues to point to a reservoir of this virus, or a similar virus, in bat populations."
Since there are no bat colonies in Wuhan and its surrounding region, the expert explained, they tried to find "other animal species that could have contributed to introducing the virus" to the city. "It doesn't appear that there was widespread circulation of the virus in any animal species in the country," where Chinese scientists analyzed thousands of species without being able to identify any as particularly active carriers. Frozen products were sold at the market, "some imported," he said, in addition to domesticated wild animals and products made from them. "We have to follow this lead, both in frozen products and in semi-processed and raw products." He also emphasized that there is no "strong evidence" of virus transmission in Wuhan before December 2019 and that the first cases in the city did not occur only at the seafood market, but also "simultaneously" in other unrelated locations, the trail of which yielded no further clues.
Therefore, experts believe that blood samples should be examined in other provinces of China and in other countries, as well as bat colonies in different Asian regions or even elsewhere, he stressed regarding what he defined as an "ongoing work".
An origin outside of Wuhan
At the press conference, Liang Wannian, the head of the Chinese expert team that investigated SARS-CoV-2, went a step further, asserting that it could have circulated in other places before Wuhan. "In the two months prior to December, there is no evidence that it was in the city," Liang stated, emphasizing that the early circulation of the coronavirus occurred several weeks before the first cases were detected, which "may explain the failure to detect it in other regions" outside of China.
The epidemiologist, who also served as head of the team appointed by China to combat the epidemic, stated that the investigation of blood and antibody samples from patients in Wuhan in the second half of 2019 "does not indicate early virus activity in the city."
He said that all samples of animal products from the Huanan market tested negative, so "it is not possible to determine how the virus got there."
Embarek said the team had identified market vendors selling frozen animal products, including farmed wild animals. “Therefore, there is potential to continue following this example and take a closer look at the supply chain and the animals supplied to the market.”