Covax, meanwhile, has fallen short of its targets, delivering just 311 million doses to more than 140 countries as of Sept. 27. The effort has been hamstrung by delays in shipments from a key manufacturer of the shots, the Serum Institute of India. Earlier this year, India halted exports to tackle a devastating outbreak at home, yet the country is now expected to restart shipments to Covax from the quarter beginning in October.