BUDAPEST, Hungary (AP) — The head of the World Health Organization has called for a two-month moratorium on administering booster shots of COVID-19 vaccines as a means of reducing global vaccine inequality and preventing the emergence of new coronavirus variants.

WHO Director-General Tedros Adhanom Ghebreyesus told reporters in Hungary’s capital Monday that he was “really disappointed” with the scope of vaccine donations worldwide.

He called on countries offering third vaccine doses to forward what they would use for booster shots to other countries so they can increase their vaccination coverage.

Tedros said that vaccine injustice and vaccine nationalism increase the risk of more contagious variants like the delta variant emerging.

Several countries have started giving the COVID-19 booster shot or plan to administer it in the fall.

The U.S. will begin offering booster shots in September to people who were fully vaccinated eight months prior. President Joe Biden was asked about whether the U.S. should be giving booster shots while other countries struggle to get the vaccine. He said that the U.S. can help other countries and offer booster shots to its people.

"We can take care of America and help the world at the same time," Biden said.

The Biden administration announced in early August that it had donated 110 million COVID-19 vaccines to 65 different countries.