Where does COVID come from? WHO investigation begins but faces challenges

The World Health Organization (WHO) has released its plan to investigate the origins of the COVID pandemic. The research will begin in Wuhan – the Chinese city where the novel SARS-CoV-2 coronavirus was first identified – and will spread across China and beyond. Tracing the trajectory of the virus is important to prevent future virus outbreaks, but scientists say the WHO team faces a daunting task.

Most researchers believe the virus originated in bats, but how it jumped to humans is unknown. Other coronaviruses have passed from an intermediate animal host; for example, the virus that caused an outbreak of Severe Acute Respiratory Syndrome (SARS) in 2002-2004 likely came from raccoon dogs (Nyctereutes procyonoides) or civets.

“Finding an animal infected with SARS-CoV-2 is like looking for a needle in the world’s largest haystack. They may never find a “smoking bat” or other animal, says Angela Rasmussen, a virologist at Columbia University in New York City. “It will be essential for investigators to establish a collaborative relationship with scientists and Chinese government officials.”

Nailing down the origins of a virus can take years, if it can be done, and the investigation will also have to navigate the highly sensitive political situation between China and the United States. US President Donald Trump “has called it a Chinese virus and the Chinese government is trying to do everything to prove that it is not a Chinese virus,” says Linfa Wang, virologist at Duke – National University of Singapore Medical School. The political blame game has meant that crucial details of ongoing research in China have not been made public, says Wang, who was part of the WHO mission that researched the origin of SARS in China in 2003. .

He hopes the situation with the new US administration will be less volatile. President-elect Joe Biden has also said he will reverse Trump’s withdrawal from the WHO. Support from China and the United States will create “a much more positive environment to conduct research in this area,” Wang said.

Research begins in Wuhan

An international team of epidemiologists, virologists and researchers with expertise in public health, animal health and food safety will lead the WHO investigation into COVID-19. The agency did not release their names.

The team held its first virtual meeting, including with researchers in China on October 30, and is reviewing preliminary evidence and developing study protocols, the WHO says. The initial phase of the investigations in Wuhan will likely be carried out by researchers already in China, and international researchers will visit the country after reviewing the results, the agency said.

In Wuhan, researchers will take a closer look at the Huanan meat and animal market, which many of the first people diagnosed with COVID-19 visited. The role the market played in the spread of the virus remains a mystery. Initial investigations sampled carcasses of frozen animals in the market, but none found evidence of SARS-CoV-2, according to a Nov. 5 report on the WHO mission’s mandate. However, environmental samples, taken mainly from sewers and sewers, have tested positive for the virus. “Preliminary studies have not generated credible leads to narrow the field of research,” the report says.

The WHO mission will investigate wild and farm animals sold in the market, including foxes, raccoons (Procyon Lotor) and the sika deer (Japanese cervus). They will also investigate other markets in Wuhan and trace the animals’ journeys through China and across borders. Investigators will prioritize animals known to be susceptible to the virus, such as cats and mink.

The team will also review Wuhan hospital records to see if the virus was spreading before December 2019. Researchers will interview the first people identified as having had COVID-19, to find out where they may have been exposed and will perform tests. tests. blood samples from medical staff, laboratory technicians and farm workers collected in the weeks and months leading up to December, looking for antibodies to SARS-CoV-2 The report acknowledges that some of this work may be be already underway in China.

Longer term plans

The initial investigation in Wuhan will inform longer-term studies into the origins of the pandemic, which could take investigators out of China. “Where an outbreak is first detected does not necessarily reflect its origin,” says the WHO report, noting preliminary reports of viral RNA detected in sewage samples before the first cases have been identified.

This statement could refer to a study¹, posted on the peer-reviewed medRxiv pre-print server, which retrospectively tested Spanish wastewater samples from March 2019 and found fragments of SARS-CoV-2, says Raina MacIntyre, epidemiologist at the University of New South Wales in Sydney, Australia. “If this study was correct, we have to ask ourselves what the virus was like in Spain in March of last year,” she says.

Plans to look beyond China are reasonable, given that extensive monitoring of bats in China since the 2002 SARS outbreak has only identified a distant relative of SARS-CoV-2, says Wang. A growing number of experts believe that the immediate or close ancestors of SARS-CoV-2 are more likely to exist in bats outside of China, Wang says. He says the WHO team should investigate bats and other wildlife in Southeast Asia for anti-SARS-CoV-2 antibodies.

The investigation should also prioritize carnivorous mammals bred for fur, such as raccoon dogs and civets, which played a role in the SARS outbreak, said Martin Beer, a virologist at the Federal Research Institute. on animal health in Riems, Germany. “It’s surprising that there is no mention of these animals in the report, and we have no information from China as to whether these animals have been tested,” Beer says.

A WHO spokesperson said the mission will be science-driven and “will be open-minded, iterative, not ruling out any hypotheses that could help generate evidence and narrow the scope of research.” they declared.