US agencies examine reports of early Covid-19 infections in Wuhan lab

Members of the World Health Organization team investigating the origins of the COVID-19 coronavirus visit the Wuhan Institute of Virology in Wuhan

Among those throwing their weight behind the former "lab leak" theory were former US President Donald Trump and many of his Republican Party colleagues.

It remained unclear whether these researchers were hospitalized or what their symptoms were, one of the sources said. "We need data. We need an independent investigation".

"Phase 2 of the COVID origins study must be launched with terms of reference that are transparent, science-based, and give global experts the independence to fully assess the source of the virus and the early days of the outbreak", US health secretary Xavier Becerra said in a video message to the annual ministerial meeting of the World Health Organization.

Three researchers from China's Wuhan Institute of Virology (WIV) sought hospital care in November 2019, a month before China reported the first cases of Covid-19, the Wall Street Journal reported on Sunday, citing a United States intelligence report.

US intelligence agencies are examining reports that researchers at a Chinese virology laboratory were seriously ill in 2019, a month before the first cases of COVID-19 were reported, according to USA government sources who cautioned that there is still no proof the disease originated at the lab.

A senior White House coronavirus adviser, Andy Slavitt, said the world needs to "get to the bottom" of the origins of the COVID-19 pandemic and added that the WHO and China need to do more to reach the definitive answers in the matter. This new information could renew calls from scientists and global leaders for a detailed probe into the origins of the coronavirus pandemic that is still wreaking havoc in several parts of the world.

Zhao Lijian said the latest claims were "totally untrue".

"The US continues to hype the lab leak theory", the ministry told the WSJ.

"We continue to have serious questions about the earliest days of the COVID-19 pandemic, including its origins within the People's Republic of China", said a spokeswoman for the National Security Council.

The coronavirus was first detected in the Wuhan region of China, with authorities there insisting it likely spread to humans from produce at an animal market.

The report said the virus jumping from bats to humans via an intermediate animal was the most probable scenario, while it dismissed a theory involving the virus leaking from a laboratory as "extremely unlikely".

The problem is, this link still hasn't been found, Scott Gottlieb, a former head of the Food and Drug Administration, told CNBC on Monday - and not for want of trying.

However, after the report was released, World Health Organization chief Tedros Adhanom Ghebreyesus insisted all theories remained on the table.

Even as all sides stress the urgency of solving the mystery of the origin, there seems to be little progress toward the next steps. When Sen. Tom Cotton, R-Ark., suggested the coronavirus was connected to research being done in Wuhan, China, the Washington Post said Cotton was pushing a "fringe theory".

On Tuesday, the United States and other countries called for a more in-depth probe into the pandemic's origins, after an worldwide mission to China earlier this year proved inconclusive.