Democrat Joe Biden opened his widest lead in a month in the US presidential race after President Donald Trump tested positive for the coronavirus, and a majority of Americans think Trump could have avoided infection if he had taken the virus more seriously, according to a Reuters/Ipsos poll released on Sunday.

The Oct 2-3 national opinion poll gave little indication of an outpouring of support for the president beyond Trump’s core group of followers, some of whom have gathered outside Walter Reed National Military Medical Center, where the president has been hospitalised...