"This is consistent with the State Department bulletin, the timing that would put it sufficiently early that it could have triggered this epidemic, the timing of these infections put it within this realm [of possibility]," Gottlieb told CNBC in an interview. "The side of the ledger that said this could have come out of a laboratory has continued to grow."
A year ago, the theory that COVID-19 originated in Nature and was spread from animals to the human population appeared somewhat plausible but no evidence at all to support it had ever emerged, Gottlieb explained.
"We found no evidence of this virus in an animal anywhere. We haven’t found the true source of the virus. With MERS and SARS we had found the intermediate host by this point," he said.
However, although the circumstantial evidence continued to grow that the outbreak had originated in the Wuhan laboratory, unless a whistleblower emerged, no hard evidence or decisive conclusion was going to appear, Gottlieb concluded.
This comes after the Chinese Foreign Ministry refuted US media reports suggesting that three employees of the Wuhan Institute of Virology fell gravely ill right before the outbreak of COVID-19. According to the latest report by an international expert group on its mission to Wuhan, the coronavirus outbreak was unlikely caused by a leak from a laboratory in Wuhan, while the virus was most likely transmitted to humans from bats through an intermediary animal.
According to Director of National Intelligence Avril Haines, the US intelligence community still does not know the origins of the COVID-19 virus and believes it could have emerged naturally after a human contact with an animal or through a laboratory accident.