GENEVA (AP) — The head of the World Health Organization is calling on rich countries with large supplies of coronavirus vaccines to refrain from offering booster shots through the end of the year, expanding a call that has largely fallen on deaf ears.

The WHO head also said Wednesday he was “appalled” at comments by pharmaceutical manufacturers who said vaccine supplies are high enough to allow for both booster shots for people in well-supplied countries and first jabs in poorer countries that face shortages.

The WHO chief said: “I will not stay silent when companies and countries that control the global supply of vaccines think the world’s poor should be satisfied with leftovers."

The U.S. and others have already begun some booster shots.