The World Health Organization (WHO) is again telling rich countries to stop hoarding COVID-19 vaccines because "vaccine nationalism" leaves none for poorer countries.

WHO Director-General Dr. Tedros Adhanom Ghebreyesus on Monday blasted rich nations for the growing inequity in vaccine distribution. The stockpiling of vaccines by rich countries is taking the world to the brink of a "catastrophic moral failure," said Tedros.

He also said the inequitable distribution of COVID-19 vaccines between rich and poor countries will prolong the global pandemic.

"More than 39 million doses of vaccine have now been administered in at least 49 higher-income countries," according to Tedros.  "Just 25 doses have been given in one lowest-income country. Not 25 million; not 25,000; just 25." He did not identify the country.

Tedros is also afraid rich countries will renege on their promise to set aside vaccines for poorer countries.

"I need to be blunt:  the world is on the brink of a catastrophic moral failure-and the price of this failure will be paid with lives and livelihoods in the world's poorest countries," he said.

WHO is pushing aggressively ahead with its own COVAX vaccine initiative, an international project to deliver safe and effective vaccines to the world's poorest to cover at least two billion vaccine doses by the end of 2021. COVAX will start rolling-out vaccines to poor and middle-income countries in February.

On Monday, WHO also said it is in advanced negotiations with Pfizer about including the Pfizer/BioNTech COVID-19 vaccine in its portfolio of shots to be shared with poorer countries.

"We are in ... detailed discussions with Pfizer," said Dr. Bruce Aylward, Senior Advisor on Organizational Change to the WHO Director-General. "We believe very soon we will have access to that product."

WHO already has deals with AstraZeneca and the Serum Institute of India, among other vaccine suppliers.