Over the weekend, China's foreign ministry noted that the WHO-led team concluded a lab leak was extremely unlikely after a visit to Wuhan in February, and blamed the USA for continuing to "hype the lab leak theory".
World Health Organization chief Tedros Adhanom Ghebreyesus himself fuelled the theory, calling for further investigations into the Wuhan Institute of Virology despite the highly-anticipated joint report stating the theory was "highly-unlikely".
'For nearly 18 months, health and care workers all over the world have stood in the breach between life and death, ' WHO director-general Tedros Adhanom Ghebreyesus told the opening of the organisation's main annual assembly.
He was talking later report The Wall Street Journal claimed that three scientists at the Wuhan Institute of Veterinary Medicine became ill in November with symptoms like Covid-19, a month before the first official case was reported. We're talking about a lab accident.
Zhao Lijian said the latest claims were "totally untrue".
Even the nation's top infectious disease expert Dr Anthony Fauci admitted that he was "not convinced" that the virus is naturally occurring.
Tedros Adhanom Ghebreyesus warned countries against becoming complacent and praised health care workers battling on the frontlines of the COVID-19 pandemic.
"Now we must honour our departed by taking urgent action this year - to strengthen health security and pandemic preparedness so that we are better prepared for the next global health crisis", he said.
It would also mean developing surge capacity for the global manufacturing of personal protective equipment, vaccines, therapeutics, diagnostics, and the healthcare workforce, the United States health secretary said. "Understanding how the coronavirus and the pandemic began matters".
As member states of the WHO, "we need to come together and finish this fight against COVID, our greatest test", he said, adding that all must fully implement and adhere to obligations under the International Health Regulations. We were not-during that first phase of the investigation, there was not access to data, there was not information provided. And that's something we've called for many, many times.
The long-delayed report, by the team of worldwide experts sent to Wuhan and their Chinese counterparts, drew no firm conclusions on the origins of the pandemic.
Meanwhile, the former head of the US Food and Drug Administration (FDA) has said that circumstantial evidence of Covid-19 originating in a lab in China's Wuhan continues to grow as researchers are yet to prove that the virus jumped from an animal to humans, as per a report in The Hill newspaper.
Meanwhile, a group of prominent scientists with relevant experience recently criticised the World Health Organization report for not taking the lab-leak theory seriously enough - it was dismissed in a few pages of a several hundred page report.
"It was obvious to me from the beginning, but as always I was badly criticized".
"We must take hypotheses about both natural and laboratory spillovers seriously until we have sufficient data", a group of researchers from top U.S. universities wrote in a letter published by the journal Science in mid-May. "Now they are all saying 'He was right.' Thank you!"