The AstraZeneca office building in Brussels. Image Credit: AP

The World Health Organisation (WHO) gave emergency use approval to AstraZeneca's COVID-19 vaccines on Monday, allowing distribution to some of the world's poorest countries to begin.

"The WHO today listed two versions of the AstraZeneca-Oxford COVID-19 vaccine for emergency use, giving the green light for these vaccines to be rolled out globally through Covax," a WHO statement said, referring to the programme aimed at equitable distribution of doses.

The two versions given the seal of approval are being produced by the Serum Institute of India (SII), and in South Korea.

"Countries with no access to vaccines to date will finally be able to start vaccinating their health workers and populations at risk, contributing to the Covax facility's goal of equitable vaccine distribution," said Dr Mariangela Simao, the WHO assistant-director general for access to medicines.

"But we must keep up the pressure to meet the needs of priority populations everywhere and facilitate global access. To do that, we need two things - a scale-up of manufacturing capacity, and developers' early submission of their vaccines for WHO review."

The UN health agency's emergency use listing procedure assesses the quality, safety and efficacy of COVID-19 vaccines and is a prerequisite for vaccines in the Covax facility.

WHO approval also allows countries to expedite their own regulatory approval to import and administer COVID-19 vaccines.

The Pfizer-BioNTech COVID-19 vaccine is the only other one to have been given the WHO green light so far.

AstraZeneca vaccines from India and South Korea made up almost all of the doses in the Covax facility's first wave of distribution.

The distribution list issued on February 3 broke down the programme's initial 337.2 million doses. First deliveries are expected in late February.

Some 145 participating economies are set to receive enough doses to immunise 3.3 per cent of their collective population by mid-2021.

The distribution list includes 240 million AstraZeneca doses from the SII; 96 million AZ doses being produced in South Korea; and 1.2 million Pfizer doses.

Both vaccines require two injected doses.