Opening the 148th session of the World Health Organization's (WHO) Executive Board, WHO Director-General Tedros Adhanom Ghebreyesus on Monday warned of the moral consequences of the lack of COVID-19 vaccines for poorer countries, saying that the higher-income countries are privileged compared to the developing countries.

"More than 39 million doses of vaccine have now been administered in at least 49 higher-income countries. Just 25 doses have been given in one lowest-income country. Not 25 million, not 25 thousand, just 25," he emphasized.

"I need to be blunt: the world is on the brink of a catastrophic moral failure," he said.

Tedros also called on countries with bilateral deals with vaccine producers to be "transparent on these contracts with COVAX, including on volumes, pricing and delivery dates" and to prioritize supplying COVAX.

COVAX is a WHO-led global initiative aimed at working with vaccine manufacturers to provide countries worldwide equitable access to safe and effective vaccines.

To highlight the current situation, the theme of World Health Day 2021 will be health inequality, he said.

"My challenge to all member states is to ensure that by the time World Health Day arrives on 7 April, COVID-19 vaccines are being administered in every country," he said.

As the world is struggling to contain the pandemic, vaccination is underway in some countries with the already-authorized coronavirus vaccines.

Meanwhile, 236 candidate vaccines are still being developed worldwide -- 63 of them in clinical trials -- in countries including Germany, China, Russia, Britain and the United States, according to information released by WHO on Jan. 12.