LONDON : The chief scientist at the World Health Organization says the agency hopes there will be about 2 billion doses of a vaccine against COVID-19 by the end of next year that would be reserved for “priority populations."Dr Soumya Swaminathan told a press briefing: “It's a big if because we don't have any vaccine that's proven." She said that because of the numerous vaccine candidates currently being tested, WHO hoped at least some might prove ready for use next year.Swaminathan said that WHO recommends immunizing people at risk first, including the elderly and those with underlying conditions like diabetes or respiratory disease, as well as key workers.But Swaminathan noted that there was still no strategy regarding any possible global.