The poor and weakest members of society should get preferential treatment when a vaccine for the coronavirus is ready, Pope Francis told the United Nations on Friday.

Speaking from the Vatican in a video address to the UN General Assembly, Francis said the worldwide pandemic had highlighted the urgent need to promote public health and ensure access to vaccines.

"If anyone should be given preference, let it be the poorest, the most vulnerable, those who so often experience discrimination because they have neither power nor economic resources," he said.

Francis has said rich countries should not hoard a coronavirus vaccine and the World Health Organization has warned against "vaccine nationalism", urging countries to join a global pact to share vaccine hopefuls with developing countries.

More than 150 vaccines are in development, about two dozen are in human studies and a handful are in late-stage trials.

In other parts of his address, he repeated calls for rich countries to reduce or forgive debts that are burdening poor countries.

He called for changes in economic and financial institutions so they can better "respond to the rapidly growing inequality between the super-rich and the permanently poor."

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