CRISPIAN BALMER and FRANCESCO GUARASCIO LEADERS of the world's largest economies kicked off a global health summit on Friday, where drugmakers were expected to promise cut-price supplies of vaccines for poorer nations to help end the COVID-19 pandemic. The Group of 20 nations looked set to call for voluntary licensing and technology transfers to enable a rapid increase in vaccine production, but will sidestep a push from the United States and other nations to waive valuable patents for shots. The European Union will also promise to set up vaccination manufacturing hubs in Africa, which faces a dearth of doses. The…