At least a fifth of the world's population may not have access to a Covid-19 vaccine until 2022, according to a study, with wealthier nations reserving more than half of next year's potential doses.

With hopes that vaccines can bring an end to a pandemic that has killed some 1.6 million people, countries including the United States, Britain and the United Arab Emirates have already begun rolling out immunisation programmes.

Eager to increase their chances of having access to at least one of the dozens of vaccines in development, many nations have snapped up allocations of several different drugs.

Wealthy nations — accounting for just 14 per cent of the global population — have pre-ordered just over half of the vaccine doses expected to be produced by the 13 leading developers next year, researchers from the Johns Hopkins Bloomberg School of Public Health found.

There are fears that poorer nations will be left behind.

Read full story here.