US President Donald Trump claimed on Sunday that he is now "immune" from the coronavirus, though medical research has suggested it is possible to be re-infected with the virus.

"It seems like I'm immune, so I can go way out of a basement," Trump said in an interview on Fox News. "It looks like I'm immune for, I don't know, maybe a long time, maybe a short time. It could be a lifetime. Nobody really knows," Trump added, Xinhua news agency reported.

White House physician Sean Conley said on Saturday that the president, who tested positive for Covid-19 on October 1 and was later hospitalized for three days before returning to the White House with continued treatment, is "no longer considered a transmission risk to others." However, Conley did not disclose when Trump last had a negative test result.

A study published in September in the journal Nature Medicine, however, indicated that recovery from the coronavirus does not confer lifetime immunity. Before and after Trump's infection, a number of White House staff members have also tested positive for the virus.