UN Secretary-General Antonio Guterres appealed on Thursday for $8 billion to equitably vaccinate 40% of people in all countries by the end of the year as the World Health Organization launched a plan aiming to inoculate 70% of the world by mid-2022.

"Crucially, the success of this plan requires equitable distribution," Guterres told reporters.

"Without a coordinated, equitable approach, a reduction of cases in any one country will not be sustained over time. For everyone's sake, we must urgently bring all countries to a high level of vaccination coverage," Reuters quoted him as saying.

Guterres pushed the Group of 20 rich countries to deliver on their "desire to get the world vaccinated" at a summit in Rome later this month.