"I said 'uh oh,'" Fauci, chief medical advisor to President Joe Biden, told the podcast Science Vs.

when asked what was going through his mind as the number of cases in the US outbreak kept growing and growing.

Unlike past monkeypox diagnoses logged in the US, this year's cases haven't been confined to prairie dog owners and their close contacts, nor were they the result of recent travel to West Africa.

At the time, Fauci thought maybe "it was just a fluke," he told journalists gathered at a vaccine conference in 2019.

"As it evolved, literally week after week after week, you'd get the unfolding and the evolution of the epidemiology — which made it clear that it wasn't restricted just to gay men," Fauci said