Medical journal The Lancet's chief editor has said that US President Donald Trump's statement that a Covid-19 vaccine could be delivered by the end of October is "simply wrong."

In a Skype interview with CNN, Richard Horton, editor-in-chief of The Lancet, said there will not be a vaccine available for public use by the end of October and President Trump is simply wrong about that.

"If we make a mistake and licence a vaccine too early - just think - we have already got a growing anti-vaccine movement, which is extremely disturbing. We can't cut corners. There will not be a vaccine available for public use by the end of October," Horton was quoted as saying to CNN.

"President Trump is simply wrong about that. I have no understanding why he is saying it. Because his advisers will surely be telling him that that's just impossible," Horton added. Horton also said the results of a Russian-developed vaccine are "encouraging" but that it would be "highly premature to think that this is the basis for a successful vaccine for public use," in part since its study involved a very small number of volunteers.

Horton is not the only one who had harsh words on Trump's timetable for a U.S. coronavirus vaccine. This year's Democratic vice-presidential nominee Kamala Harris also lashed out at Trump Saturday, saying she would not trust the president's words on the safety of any coronavirus vaccine approved for use in America before the November election.