A Unicef official has said poorer nations last month rejected more than 100 million doses of Covid-19 vaccines distributed by the global programme Covax, mainly because of a rapidly approaching expiry date.

The big figure shows the difficulties of vaccinating the world's population, despite growing supplies of shots, with Covax getting closer to delivering one billion doses to nearly 150 countries.

"More than 100m have been rejected just in December alone," Etleva Kadilli, director of the supply division at the UN agency, told lawmakers at the European Parliament, adding that the main reason for rejection was their short shelf life.

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