The website was also critical of steps such as social distancing, mask mandates and lockdowns.
Trump began a 12-month process of withdrawing the US - by far the WHO's largest financial backer - from the agency when he took office in January.
Fauci, Biden and WHO had no immediate comment.
Soon after taking office, Trump also said that Fauci, who has faced threats since leading the country's Covid-19 response, should hire his own security and ended US security for him.
A CIA spokesperson said in January that the CIA had assessed that the Covid-19 pandemic was more likely to have emerged from a lab than from nature. The CIA had said it had "low confidence" in its assessment and that both scenarios - lab origin and natural origin - remained plausible.
China's government says it supports and has taken part in research to determine Covid-19's origin, and has accused Washington of politicising the matter, especially because of efforts by US intelligence agencies to investigate.
Beijing has said there is no credibility to claims that a laboratory leak likely caused the pandemic.
