Dr. Peter Ben Embarek from the World Health Organization (WHO) was speaking during a press conference in Wuhan, China, at the end of a four-week mission to the city where the new coronavirus first emerged in December 2019.
“Our initial findings suggest that the introduction through an intermediary host species is the most likely pathway and one that will require more studies and more specific targeted research”, he said.
Joint expert team
The international team convened by WHO consisted of 17 Chinese experts and an equal number of counterparts from other nations, looking at three areas: epidemiology, molecular research and animal and environment.
They visited hospitals and other sites in Wuhan, including the Huanan Market where the SARS-CoV-2 virus was first detected, and identified four main hypotheses of how it could have been transmitted to humans.
“However, the findings suggest that the laboratory incident hypothesis is extremely unlikely to explain introduction of the virus into the human population, and therefore is not a hypothesis that implies to suggest future studies into our work, to support our future work, into the understanding of the origin of the virus”, Dr. Embarek said.
Frozen food link?
While ongoing research continues to suggest that bats are a natural reservoir for the new coronavirus, Dr, Embarek ruled out the possibility in Wuhan, as the city is not near to any environments where these animals are found.
One hypothesis suggests the virus could have come through the food chain, as frozen products can provide a surface for transmission.
Dr. Embarek said frozen animal products, mainly seafood, were sold at Huanan Market, along with products made from wild and farmed animals, some of which came from other parts of China or were imported.
“So, there is the potential to continue to follow this lead and further look at the supply chain and animals that were supplied to the markets in frozen and other processed and semi-processed form, or raw form”, he said.
Virus circulating elsewhere earlier
It has been nearly a year since the COVID-19 pandemic was declared and as of Tuesday, there were more than 106 million cases worldwide, including some 2.3 million deaths.
The investigations conducted in Wuhan will lay the groundwork for virus origin tracing elsewhere, according to the team’s Chinese lead, Dr. Liang Wannian.
He said their review of unpublished studies suggests the virus was circulating earlier in other regions.
“These studies from different countries suggests SARS-CoV-2 circulation preceding the initial detection of cases by several weeks”, said Dr. Liang, speaking through an interpreter.
“Some of the suspected positive samples were detected even earlier than the first case reported. This indicates the possibility of the missed reported circulation in other regions.”
Dr. Liang added that research also found “no indication” of virus transmission in Wuhan in the period before December 2019.