The World Health Organization (WHO) says the world needs 11 billion doses of COVID-19 vaccines to ensure at least 70 percent of every country's population is vaccinated by mid next year.

The figure was announced on Tuesday by the WHO Director-General Tedros Adhanom, who expressed his organizations gratitude to the G7 countries for pledging some 870 million doses.

"I have called for a massive push to vaccinate at least 10% of the population of every country by September, at least 40% by the end of this year, and at least 70% by the middle of next year," said Tedros.

"To reach these targets, we need 11 billion doses. We're grateful for the announcements made by the G7 countries that together they will donate 870 million doses, primarily through COVAX. But much more is needed, much faster."

Tedros noted that some countries were yet to receive the life-saving jabs, while others have not received enough.

The WHO chief said the world was facing a challenge as the virus continues to evolve, resulting in more transmissible variants.

He noted that the Delta COVID-19 variant is now in more than 111 countries and is expected to soon be the dominant COVID-19 strain circulating worldwide.

Tedros urged countries to continue adhering to health protocols to keep the virus at bay, despite the ongoing vaccination campaigns.