IMF managing director Kristalina Georgieva and the heads of the World Bank Group, World Health Organisation and World Trade Organisation have expressed concern in a joint statement that it will not be possible to vaccinate at least 40 per cent of the population in all countries by the end of 2021 without urgent action.

Wide disparities in vaccination rates in advanced economies and developing countries will be a key issue during a virtual global summit the US is organising on the sidelines of the UN General Assembly.

IMF spokesman Gerry Rice told reporters on Thursday that President Joe Biden had invited Georgieva to speak at the September 22 event, which has not yet been formally announced by the White House. A White House spokesman declined to comment.

Reuters reported this week that the US was pushing global leaders to endorse an even more ambitious vaccination target at the summit: getting 70 per cent of the world's population vaccinated by the time of the 2022 General Assembly.

The leaders said countries with high vaccination rates - which have collectively pre-purchased more than two billion doses more than needed - should urgently swap their near-term delivery schedules with global distribution programs to help address gaps in low- and middle-income countries.

They urged high-income countries to fulfil their dose donation pledges and release vaccine companies from contracts so those doses can be delivered to people in need.

The group also urged vaccine manufacturers to prioritise and fulfil their contracts to COVAX and AVAT, an African distribution program.

Australian Associated Press