US presidential rivals spar over Covid-19 vaccine - 2020-09-08
President Trump again hinted that a vaccine might be available before the November presidential election and accused his Democratic rivals of "reckless anti-vaccine rhetoric".
Mr Biden expressed scepticism that Mr Trump would listen to the scientists and implement a transparent process.
The US has six million cases of coronavirus, the highest in the world.
The virus has also claimed nearly 190,000 lives and fuelled a major recession, double-digit unemployment and sagging consumer confidence.