Former UK prime minister Gordon Brown warned world leaders that the pandemic is becoming a “man-made catastrophe” as inoculation rates struggle to gather pace in poor countries.
The call for immediate action came as the foreign ministers of the world's leading economies gathered in London on Tuesday for the first face-to-face meeting of the G7 in more than two years.
The Access to Covid-19 Tools Accelerator programme – which aims to find, develop and distribute coronavirus shots, tests and therapeutics to poor nations – is $19 billion short of this year’s $22bn target.
The World Health Organisation said an additional $35bn to $45bn would be needed next year to ensure most adults around the world are immunised.
Mr Brown said the G7 could secure a “historic breakthrough” on tackling the pandemic collectively.
“This is a man-made catastrophe,” he said. “By our failure to extend vaccination more rapidly to every country, we are choosing who lives and who dies. I say the world is already too deeply divided between rich and the poor to allow a new unbridgeable divide to become entrenched by the vaccinated, who live, and the unvaccinated, who are dying.”
WHO chief Tedros Adhanom Ghebreyesus urged the G7 to take decisive action at its June summit, to be hosted by British Prime Minister Boris Johnson in Cornwall, south-west England.
"The G7 countries are the world's economic and political leaders. They are also home to many of the world's vaccine producers," Dr Tedros said.
"We will only solve the vaccine crisis with the leadership of these countries."
Based on national income, wealth and benefits from the resumption of trade, Mr Brown said that the US should pay 27 per cent of the cost of vaccinating the populations of poor nations; Europe 23 per cent; Japan six per cent; Britain five per cent; and Canada – plus South Korea and Australia, also attending the G7 – two per cent each.
He said he detected a change in Washington's attitude towards vaccine licensing agreements and temporary intellectual property rights waivers, which could expand production capacity.
Nearly 1.2 billion Covid-19 vaccine doses have been administered worldwide, but only 0.2 per cent in the 29 lowest-income countries, home to nine per cent of the global population.
The Covax global vaccine-sharing programme is competing with rich countries striking their own deals with manufacturers.
The main supplier to Covax is the Serum Institute of India, which is producing AstraZeneca vaccines.
But increased demand for doses in India, where the pandemic is raging, has interrupted Covax supplies.
Bruce Aylward, the WHO lead on Covax, said Covax had missed out on 100 million anticipated doses, and acknowledged there was still no fixed date for when the institute would resume deliveries.
Dr Tedros said that more new Covid-19 cases were reported in the past two weeks than during the first six months of the pandemic, with India then Brazil making up most of them.
Covax announced on Monday that it struck a deal to buy 500 million doses of the Covid-19 vaccine developed by Moderna, with 34 million doses of the two-shot vaccine due in the final quarter of 2021 and 466 million next year.
Under Covax, the cost of vaccines for the 92 poorest countries is covered by donors.
More than 49 million Covid-19 vaccine doses have been shipped worldwide under the initiative.
UK Trade Secretary Liz Truss said on Tuesday that Britain was looking into boosting Covax supplies.
“Nobody is safe until everybody is safe,” she said.