Covishield is a licensed version of the AstraZeneca shot made by the Serum Institute of India (SII), the world's biggest vaccine maker.
SII has nearly quadrupled its output of Covishield to up to 240 million doses a month since April, when India stopped all exports in order to inoculate its own people during a surge of cases.
"There will need to be purchase orders confirmed to SII, labelling and packing, export authorisation granted for each of these shipments," said the source. "So the first deliveries, assuming the Indian government grants export authorisation, won't happen until a few weeks from now." A WHO spokesperson said in an email that a new COVAX supply forecast would be published next week. SII and India's health ministry did not respond to requests for comment.