Bats are the most likely source of the COVID-19 pandemic, according to a report released by World Health Organization (WHO) investigators tasked with finding the cause of the disease that has killed nearly 3 million people in the past 15 months.
At a news conference, lead investigator Peter Ben Embarek said the four-week visit to Wuhan, China turned up no indication that SARS-CoV-2, the virus that causes COVID-19, was spreading in Wuhan or surrounding areas before December 2019.
Since the outbreak was detected at Wuhan’s Huanan Seafood Wholesale Market, 127.3 million people around the world have contracted COVID-19. In Africa, COVID-19 had infected nearly 4.2 million people and killed more than 112,000 as of March 29, according to the Africa Centres for Disease Control and Prevention.
The Huanan market sits about 15 kilometers across the Yangtze River from the Wuhan Institute of Virology, which some people still consider a potential source of the global outbreak. The WHO investigators say that a release from the institute is “extremely unlikely.” The team visited the institute and reviewed research and safety protocols there.
“Nobody has been able to pick up any firm evidence that any of the labs would have been involved in this,” Embarek said during the press conference.
However, responding to the report, WHO Director-General Dr. Tedros Adhanom Ghebreyesus said the lab-leak theory deserves more scrutiny. “I do not believe that this assessment was extensive enough,” he said.
In an open letter published in The Wall Street Journal and France’s Le Monde newspaper, an international team of scientists led by Jamie Metzl, a virus expert who serves on a WHO genetic engineering advisory committee, expressed doubt at the report’s conclusion.
They say the WHO investigative team was compromised by conflicts of interest and restrictions from China. They want another investigation that addresses the lab-release hypothesis and other questions in a “thorough, credible and transparent investigation.”
“My summary is that the Wuhan investigation is a sham — a public relations exercise orchestrated by the Chinese government,” one of the letter’s signers, Dr. Colin Butler of Australia’s National Centre for Epidemiology and Population Health, told ADF.
The WHO investigation, which began in January, has received criticism from other circles for starting more than a year after the initial outbreak. Other criticism has focused on Chinese authorities, who refused to turn over raw data from their own investigation of the market and the infections that arose there.
Embarek stressed during the news conference that the investigation was designed to be a collaboration between Chinese scientists and the international team. Although the group felt political pressure from inside and outside China, the scientists worked together openly and still have much work to do, he said.
Investigators traced the live animals sold at the Huanan market around the time of the outbreak to the farms in southern China that raised them.
“There’s clear evidence that there was a pathway into the market for animals that were able to carry coronaviruses,” team member Peter Daszak, a zoologist and expert on animal-to-human disease transmission, said during the news conference.
Investigators found evidence of SARS-CoV-2 in the live-animal section of the Huanan market, according to bat expert Linfa Wang of Singapore, a virologist who was part of the investigative team.
Soon after the outbreak, the Chinese government banned the raising of wild animals for food, an indication that authorities felt the virus outbreak likely began on a farm, Daszak has said.
The next step, according to Daszak, is to interview farmers in southern China to see whether anyone experienced COVID-19 symptoms before the pandemic broke loose in Wuhan.
Finding the origin of SARS-CoV-2 requires a great deal more work. “It will take some time and depend on a good portion of luck,” Embarek added.