The World Health Organization says Wuhan is not necessarily where the pandemic started

Although the first clusters of atypical pneumonia were reported in Wuhan, China, it doesn't necessarily mean it's where the COVID-19 disease crossed from animals into humans, a senior World Health Organization (WHO) expert said on Monday (August 3).

Dr. Michael Ryan, executive director of the WHO Health Emergencies Program, said at a routine COVID-19 briefing on Monday, that a much more "extensive retrospective epidemiological study" should be taken to fully understand the links between the cases.

He stressed the need to start studies on the first reported human clusters to systematically look for the "first signal at which the animal-human species barrier was crossed," before moving to the studies on the animal side.

The WHO advanced team that traveled to China in preparation for an international mission of identifying the zoonotic source of COVID-19 has concluded its mission recently, according to the WHO expert.

Future studies will build on the initial investigations done by Chinese experts around the Wuhan seafood market.

"What is required is going to be a much more extensive retrospective epidemiologic study to look at those first cases and clusters in Wuhan, and to fully understand the links between those cases, so that we can then determine at what point in Wuhan or elsewhere, was the animal-human species barrier breached.

Again, one must remember that there was a specific surveillance system in place in Wuhan for picking up clusters of atypical pneumonia.

It was there for a very specific purpose, and the fact that fire alarm was triggered doesn't necessarily mean that is where the disease crossed from animals into humans," Michael Ryan, Executive director of the WHO Health Emergencies Program, said.