US President Donald Trump has said a vaccine against the deadly coronavirus could be three or four weeks away, despite cautionary notes sounded by some US public health officials about that accelerated timeline.

Trump, speaking at a town hall hosted by ABC News in Philadelphia, defended his handling of the coronavirus crisis, and said a vaccine could be ready for distribution before the US presidential election on November 3, Reuters reported.

“We're very close to having a vaccine,” he said. “If you want to know the truth, the previous administration would have taken perhaps years to have a vaccine because of the FDA and all the approvals. And we're within weeks of getting it [...] Could be three weeks, four weeks.”