The Covax vaccine-sharing programme said on Tuesday it will deliver 237 million doses of AstraZeneca’s Covid-19 shot to 142 countries by the end of May as it steps up the global roll-out of its vaccine supplies, according to Reuters.

The timeline for the delivery of doses, made by AstraZeneca and by India’s Serum Institute, will be split into separate two-month schedules, Covax said in a statement, with the first in February-March and the second in April-May.

“These timelines are dependent on a variety of factors including national regulatory requirements, availability of supply, and fulfillment of other criteria such as validated national deployment and vaccination plans,” the statement said.

Covax is the World Health Organisation-backed programme to provide vaccines for poor and middle-income countries. It began its roll-out last week with the first deliveries of shots to Ghana and Ivory Coast.