The head of the World Health Organisation called vaccine inequality "grotesque" as he urged producers of Covid-19 vaccines to follow AstraZeneca's lead and license technology to other makers.
WHO Director General Dr Tedros Adhanom Ghebreyesus called for more drug makers to adopt this model to boost supplies, including for the Covax vaccine-sharing programme to quickly send more shots to developing countries.
"The gap between number of vaccines administered in rich countries and the number administered through Covax is growing and becoming more grotesque every day," Dr Tedros said.
"The inequitable distribution of vaccines is not just a moral outrage. It's also economically and epidemiologically self-defeating."
AstraZeneca's shot is being produced in various locations including South Korea's SK Bioscience and the Serum Institute of India.
Interim data showed the AstraZeneca vaccine, developed with the University of Oxford, was 79 per cent effective in preventing symptomatic Covid-19 and posed no increased risk of blood clots.
WHO chief scientist Soumya Swaminathan called it a "very good vaccine for all age groups".
Sweden, Norway, Finland and Denmark have extended suspensions of AstraZeneca's vaccine as investigations continue into rare blood-clotting events.
But WHO officials said African countries receiving the vaccine through Covax are moving ahead.
"They did ask a lot of questions but the demand for the vaccine is extremely high," said WHO senior adviser Bruce Aylward.
It remains possible for Covax to hit a second-quarter goal of delivering 300 million doses, Mr Aylward said.
But he acknowledged "teething problems", with SKBioSciences and the Serum Institute hard pressed to fill Covax orders.
"We simply cannot get enough vaccine," Mr Aylward said.
"We're hoping both companies will be able to scale up and keep up with the rate of deliveries we're aiming for."