The World Health Organization is calling for high-income countries to halt booster shots until the end of September in order to allow at least 10 percent of the population of every country to be vaccinated.

Tedros Adhanom Ghebreyesus, director-general of the World Health Organization, or WHO, said on Wednesday that so far, more than 4 billion vaccine doses have been administering globally, with more than 80 percent going to high and upper-middle income countries.

Tedros said this is even though those countries account for less than half of the world's population.

"While hundreds of millions of people are still waiting for their first dose, some rich countries are moving toward booster doses," he said during a media briefing.

Although the head of the WHO said he understands that all governments want to protect its population from the Delta variant, Tedros criticized countries that have already used most of the global supply of vaccines and are now using even more of it as "the world's most vulnerable people remain unprotected".

Tedros stressed that there has to be an urgent reversal from the majority of vaccines going to richer countries, to the majority going to poorer countries.

"WHO is calling for a moratorium on boosters until at least the end of September, to enable at least 10 percent of the population of every country to be vaccinated," he said.

"To make that happen, we need everyone's cooperation, especially the handful of countries and companies that control the global supply of vaccines."

He called on the G20 countries to make concrete commitments to support WHO's global vaccination targets when the G20 health ministers meet in a month's time.

Tedros also asked for producers to prioritize COVAX, a worldwide initiative aimed at equitable access to COVID-19 vaccines, as well as people with influence such as Olympic athletes, investors and faith leaders, to support WHO's call for a pause on booster shots.

"At the same time, we must all remember that vaccines are not the only tool. Indeed, there is no single tool that will defeat this pandemic," Tedros said. "We can only defeat it with a comprehensive approach of vaccines in combination with the proven public health and social measures that we know work."