The World Health Organization (WHO) has called for a COVID-19 booster shot moratorium for wealthy countries, citing a disparity between them and poorer countries.

The moratorium would last until at least the end of September, as data from the WHO shows high-income countries administering nearly 50 doses per 100 people in the population, while low-income countries have administered about 1.5 doses for every 100 people.

“These populations need vaccines urgently, especially health workers, older people and other vulnerable groups,” Tedros Adhanom Ghebreyesus, the director general of the World Health Organization said Wednesday. “I understand the concern of all governments to protect their people from the Delta variant, but we cannot 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.”

Ghebreyesus added that the moratorium should remain until at least 10% of the population in every country can be vaccinated against COVID-19, with a majority of vaccines going to lower-income countries instead of the wealthier ones.

In early July, Pfizer-BioNTech requested FDA authorization to distribute a third shot to Americans. The FDA and CDC responded by saying, “Americans who have been fully vaccinated do not need a booster shot at this time.”

“The United States is fortunate to have highly effective vaccines that are widely available for those aged 12 and up,” the FDA and CDC added in a joint statement. “People who are fully vaccinated are protected from severe disease and death, including from the variants currently circulating in the country such as Delta. We are prepared for booster doses if and when the science demonstrates that they are needed.”