COVID-19 drug, some predict an even more disturbing scenario if a successful vaccine is developed.Dozens of vaccines are being researched, and some countries — including Britain, France, Germany and the US — already have ordered hundreds of millions of doses before the vaccines are even proven to work.While no country can afford to buy doses of every potential vaccine candidate, many poor ones can't afford to place such speculative bets at all.The key initiative to help them is led by Gavi, a public-private partnership started by the Bill & Melinda Gates Foundation that buys vaccines for about 60% of the world’s children.In a document sent to potential donors last month, Gavi said those giving money to its new “Covax Facility" would have.