Former UK prime minister Tony Blair said rumours and misinformation on the internet were leading to increasing vaccine hesitancy in poorer nations.
He said reluctance in Africa was compounding problems as some countries were turning away supplies of AstraZeneca-Oxford vaccines based on “rumours and stuff flying around on the internet”.
“You’ve got a crazy situation at the moment where you have African countries turning away the AstraZeneca vaccine on the basis it may have health problems,” Mr Blair told Sky News on Monday.
“The health problems from getting Covid are self-evidently greater than the problems you may get in a very, very limited number of cases, for example, blood clots.”
In February, South Africa sold supplies of AstraZeneca’s Covid-19 vaccine to other African Union member states after a trial showed the shot offered minimal protection against mild to moderate illness caused by the South African coronavirus variant.
Mr Blair did not identify which other African countries had declined to use AstraZeneca’s drug.
His comments came as Unicef said on Monday that G7 countries and the EU could donate 150 million Covid-19 vaccine doses while maintaining their own inoculation campaigns.
A study by British company Airfinity showed the countries could help close the world’s vaccine gap by sharing just 20 per cent of their June, July and August stocks with the Covax scheme for donated supplies.
"And they could do this while still fulfilling their vaccination commitments to their own populations," Unicef director Henrietta Fore said.
The UK is due to host its fellow G7 member states Canada, France, Germany, Italy, Japan and the US for a summit in June.
Unicef said that by then, the Covax programme, co-led by Gavi the Vaccine Alliance and the World Health Organisation, would find itself 190 million doses short of its planned supplies.
The shortfall is in part due to a devastating surge of the virus in India, which was due to manufacture and export the majority of Covax doses but is now using its supply domestically.
With additional shortages in supplies and funding, Unicef called for swift action until more sustainable production models are within reach.
"Sharing immediately available excess doses is a minimum, essential and emergency stopgap measure, and it is needed right now," it said.
Mr Blair said only 30 million doses had been delivered to Africa, a continent with a 1.2 billion population.
“The biggest problem we have now is that even if we do everything (in the UK) … the problem is that variants can come back into our own country and you see this with the India variant now,” he said.
“The important thing is at the same time we vaccinate our own people, what we do is set up a detailed plan for the international community to maximise production and distribute to all parts of the world.”
The US has 60 million AstraZeneca doses it could share, while France has pledged 500,000 doses and Sweden 1 million, with Switzerland considering a similar donation.
About 44 per cent of the 1.4 billion doses of Covid-19 vaccines administered globally have been in high-income countries accounting for 16 per cent of the world’s population.
Only 0.3 per cent have been administered in the 29 lowest-income countries, home to nine per cent of the world's population, Unicef said.
The gap spurred World Health Organisation chief Tedros Adhanom Ghebreyesus to ask vaccine-wealthy nations to refrain from inoculating children and adolescents and instead donate doses to Covax.
Unicef reiterated the need to vaccinate poorer populations prevent more contagious and deadlier variants from wiping out progress towards immunity.
"We are concerned that the deadly spike in India is a precursor to what will happen if those warnings remain unheeded," it said.
"Cases are exploding and health systems are struggling in countries near – like Nepal, Sri Lanka and Maldives – and far, like Argentina and Brazil."
