The global scheme to deliver Covid-19 vaccines to poorer countries has a "very high" risk of failure, possibly leaving billions of people with no access to vaccines until as late as 2024, internal documents say.
The World Health Organisation's Covax programme is the main global scheme to vaccinate people in poor and middle-income countries around the world against the coronavirus.
It aims to deliver at least 2 billion vaccine doses by the end of 2021 to cover 20 per cent of the most vulnerable people in 91 poor and middle-income countries, mostly in Africa, Asia and Latin America.
But the scheme's promoters say the programme is struggling from a lack of funds, supply risks and complex contractual arrangements that could make it impossible to achieve its goals, internal documents seen by Reuters show.
"The risk of a failure to establish a successful Covax facility is very high," says a report to the board of Gavi, an alliance of governments, drug companies, charities and international organisations that arranges global vaccination campaigns.
Gavi leads Covax alongside the WHO.
The report and other documents prepared by Gavi are being discussed at its board meetings on December 15 to 17.
The failure of the scheme could leave people in poor nations without any access to Covid-19 vaccines until 2024, one document says.
The risk of failure is higher because the scheme was set up so quickly, operating in "uncharted territory", the report says.
The stark risk to Covax was revealed as many richer nations continued to vaccinate their most vulnerable or plan for inoculations to begin.
European Commission President Ursula von der Leyen said on Wednesday that all 27 members of the EU bloc would begin vaccinations on the same day.
"To get to the end of the pandemic, we will need up to 70 per cent of the population vaccinated. This is a huge task, a big task," she told the European Parliament.
The European Medicines Agency, which regulates the release of medicine in the EU, is bringing forward to next Monday a special meeting to discuss conditional approval for the Pfizer/BioNTech vaccine.
EU officials said that if the agency meeting gives its approval, the vaccine would be authorised two days later.
Italy, which on Tuesday became the nation with the highest death toll in Europe when it recorded a further 846 deaths, welcomed the news, but authorities urged caution in the lead-up to Christmas.
"We still need to be careful and cautious in the coming months until we have achieved sufficient vaccination coverage," Health Minister Roberto Speranza said.
"But we're on the right path and we can finally see the light at the end of the tunnel."
The Corriere della Sera newspaper reported on Wednesday that there were calls within government for the whole country to be put into a "red zone" between December 24 and January 6, with non-essential shops and restaurants closed.
Prime Minister Giuseppe Conte has already announced a ban on non-essential travel between regions and a blanket quarantine on anyone coming into the country from abroad over the holidays.
A year into the coronavirus pandemic, which has killed more than 1.6 million people and infected more than 73 million globally, the question of where the virus came from and how it first crossed over to humans remains a mystery.
The World Health Organisation said a team of international experts would travel to China next month to help investigate the animal origins of Covid-19.
