NEW DELHI : While clinical trial results of the first successful covid-19 vaccines are expected as early as the end of this year, vaccination of public will, realistically, only begin in the middle of 2021 after mass manufacturing of doses starts, World Health Organization Chief scientist Soumya Swaminathan said on Friday.“We expect results from some of the candidates which are already in phase 3 trials to come by the end of the year or by beginning of next year, following which there will be scaling of manufacturing to produce the hundreds of millions of doses that are going to be needed...