By Elizabeth Merab

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The World Health Organisation has entered the final stages of the search for the origins and exact source of Covid-19 (SARS-CoV-2), which has so far killed over 1.3 million people and infected over 55 million worldwide.

On November 10, the international health agency released its plan to identify the origins of the virus and how it first crossed over to humans in China, where the outbreak was first reported. The Chinese government remains guarded about this information.

The WHO has faced harsh criticism, especially from the Trump administration for not moving quickly enough with the probe. The UN agency first started the investigation mission in mid-February, when the world still hoped that the new coronavirus could be contained.

In May, more than 130 WHO member states, including China, passed a resolution that included a call for the inquiry with several countries pressing for the investigation to start.

“Building on the recommendations from the 73rd World Health Assembly, WHO, together with the government of China, are setting up an international multidisciplinary team to design, support and conduct a series of studies that will contribute to origin tracing work,” the dossier said.

In July, a three-week scoping mission, in which two WHO experts travelled to China, laid the groundwork for the larger investigation that was quietly released. The larger mission of international experts, including epidemiologists and animal health specialists, had been expected to start its investigation in “a matter of weeks” after that, the WHO said in July. However, these plans stalled.

According to the report, some countries retrospectively identified cases of Covid-19 weeks before the first case was officially notified through surveillance, and unpublished reports of positive sewage samples could suggest that the virus may have circulated undetected for some time. The WHO team aims to explore how the circulation of SARS-CoV-2 might have started, gather evidence from the cluster of cases identified in December 2019 for potential links and clues to its origin.

The search will start in Wuhan — the Chinese city where the virus was first identified — and expand across China and beyond.

According to the report, an international team of epidemiologists, virologists, and researchers with expertise in public health, animal health, and food safety will lead the WHO’s Covid-19 investigation. The agency has not released their names.

For Covid-19, the researchers will study samples from before and after the time the coronavirus outbreak was publicly declared in late December 2019.

“An outbreak of pneumonia of unknown cause was identified through surveillance in Wuhan, however the possibility that the virus may have silently circulated elsewhere can’t be ruled out,” the report said.

Wet market

It is widely assumed that the virus originally came from bats, but the intermediate animal host that transmitted it between bats and humans remains unknown. Scientists believe the killer virus jumped from animals to humans, possibly from a wet market in the city of Wuhan city, in the province of Huanan.

In Wuhan, researchers will take a closer look at the Huanan meat and animal market, which was closed after many of the first people diagnosed with Covid-19 were found to have visited. Early investigations sampled frozen animal carcasses at the market, but found no evidence of SARS-CoV-2, according to a November 5 report of the WHO mission’s terms of reference.

However, environmental samples, taken mostly from drains and sewage, tested positive for the virus.

“Where an epidemic is first detected does not necessarily reflect where it started,” the WHO report said, noting that preliminary reports of viral RNA detected in sewage samples before the first cases had been identified.