Richer countries are fighting over vaccine contracts and how many millions they are going to receive, while front-line workers in others are not even left with "crumbs," said the World Health Organization's Michael Ryan.
Ryan, executive director of the WHO health emergencies program, said people in richer countries needed to examine their consciences when health workers in poorer nations, who are fighting the coronavirus on the front line, are not getting the chance to receive vaccines.
"We all need to step into the place of them [nurses in poorer nations] and where they are today – fighting on the front line right now in ICUs," said Ryan.
"They are down right at the end of the queue right now and they are looking up to the top of the queue and the people at the top of the queue are fighting over where they are in the queue.
"That's what it looks like, fighting over the cake and they don't even have access to the crumbs. So I think we need to step back and reflect upon our brave colleagues and where they stand today and what we are going to do about that."
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It comes as the European Union has been disputing the roll-out of AstraZeneca vaccines and how many millions of doses the bloc should be receiving.
Some richer countries have bought more vaccines than they need to hedge their bets in case of an emergency.
"We are all desperate, everyone is desperate, governments are desperate to service the needs of their citizens, that's their mandate, but we all need to say, 'would I put a vaccine in my arm today if I thought a health worker in the [Global] South would not get a vaccine today?'" Ryan continued.
"I think we all need to examine our own consciences and then tell our political leaders and others what we want them to do."