At a White House COVID-19 Response Team virtual briefing, Fauci was asked about a recent Wall Street Journal report that said three researchers at a Chinese virology laboratory were seriously ill a month before the first cases of COVID-19 were reported.
"As I've said many times, many of us feel that it is more likely that this is a natural occurrence, as has happened with SARS-CoV-1, where it goes from an animal reservoir to a human," said Fauci. "But we don't know 100% the answer to that."
Fauci and White House senior COVID-19 adviser Andy Slavitt also called for a second phase of an investigation into the origins of the coronavirus.
"We need to get to the bottom of this and we need a completely transparent process from China," said Slavitt.