GENEVA — The World Health Organization is calling for a moratorium on booster shots until at least the end of September, WHO Director-General Tedros Adhanom Ghebreyesus said during a news briefing in Geneva on Wednesday.

"WHO is calling for a moratorium on boosters until at least the end of September to enable at least 10% of the population of every country to be vaccinated. To make that happen, we need everyone's cooperation, especially the handful of countries and companies that control the global supply of vaccines," he said.

"Even while hundreds of millions of people are still waiting for their first dose, some rich countries are moving towards booster doses," added Tedros. "So far more than 4 billion vaccine doses have been administered globally. More than 80 percent have gone to high and upper-middle-income countries, even though they account for less than half of the world's population."

Germany, the UK, and Israel have all announced plans to provide booster shots for certain vulnerable populations.

While Tedros said he understood the concern of all governments to protect their people from the Delta variant, "we cannot and we should not accept countries that have already used most of the global supply of vaccines using even more of it while the world's most vulnerable people remain unprotected."

In May, Tedros called for global support to enable countries to vaccinate at least 10 percent of their populations by September. He said that although it's more than halfway to the target date, the world is not on track.

When his challenge was issued, high-income countries had administered around 50 doses for every 100 people, Tedros said.

Since then, the number has doubled, with high-income countries having now administered almost 100 doses for every 100 people, while low-income countries have been able to administer 1.5 doses for every 100 people due to lack of supply.

"We need an urgent reversal from the majority of vaccines going to high-income countries to the majority going to low-income countries," Tedros said.

Tedros called upon the G20 leaders to make concrete commitments to support WHO's global vaccination targets, for vaccine producers to prioritize COVAX, and for everyone with influence to support the call for the moratorium on boosters. — CNN