The World Health Organization called on Wednesday for countries not to give out extra COVID-19 vaccine doses - or what is known as booster shots - until 2022, pointing to millions around the globe who are yet to receive a single dose.

World Health Organization Director-General Tedros Adhanom Ghebreyesus, speaking from the WHO headquarters in Vienna, said, "I will not stay silent when the companies and countries that control the global supply of vaccines think the world's poor should be satisfied with leftovers."

He urged wealthy countries and vaccine manufacturers to prioritize getting the vaccines to medical workers and the vulnerable populations in poorer nations over booster shots.

This comes at a time when COVID-19 cases are surging all over the world as more concerning variants, such as the Delta variant, which was proven to be highly contagious, are emerging.

"We do not want to see widespread use of boosters for healthy people who are fully vaccinated," he continued.

Last month, the WHO called for a moratorium on booster shots until October in an attempt at addressing the drastic inequity in dose distribution between rich and poor nations.

He explained that the WHO postponed the date by two months due to "a little change" in the global situations, in a nod to the emerging variants.

"So today I am calling for an extension of the moratorium until at least the end of the year," the WHO chief said.

Previously, wealthy countries had pledged to donate over one billion doses to less fortunate countries, "but less than 15% of those doses have materialized," Ghebreyesus asserted.

He urged those countries to act on their words, "We don't want any more promises. We just want the vaccines."

Some countries have been arguing for booster shots for the wide population, not only for the most vulnerable, as the emerging variants are raising concerns over vaccine efficacy, especially the highly transmissive delta variant.

The WHO would not object to vaccinating the vulnerable, as they have acknowledged that an additional jab could be needed for the immunocompromised. However, they object to giving booster doses to those who would not be compromised by the virus.