The World Health Organization (WHO) plans to approve several COVID-19 vaccines from global manufacturers in coming weeks and months, a document published on Wednesday shows, as it aims for rapid rollouts in poorer countries.

COVAX, a global scheme co-led by the WHO, wants to deliver at least 2 billion COVID-19 doses across the world this year, with at least 1.3 billion going to poorer countries.

But it has so far struggled to secure enough shots due to a shortage of funds, while wealthy nations have booked large volumes of vaccines for themselves.

In the race to deploy shots, regulatory approvals are key to confirming the effectiveness and safety of vaccines, and to boosting output. But some poorer countries rely mostly on WHO authorizations as they have limited regulatory capacity.

WHO approval does not automatically lead to purchases by the COVAX, but it could facilitate the rollout in poorer countries that can acquire the vaccines directly.

So far, two Chinese vaccine makers, Sinopharm and Sinovac, have filed their applications with the WHO. The agency is now reviewing them and could make decisions on both in March at the earliest, the document says.

Sinopharm's vaccines have been approved by China, the United Arab Emirates and Bahrain for general use and have been authorized for emergency use in Pakistan, Serbia and Egypt.

Sinovac has yet to release global results of its Phase III trials, but its vaccine has been approved for emergency use in countries including Brazil, Indonesia, Turkey and Chile.

Read more: A glimmer of hope for developing countries as Chinese COVID-19 vaccines enter final trials

Other vaccine candidates 

The WHO authorized the vaccine developed by Pfizer and its German partner BioNTech at the end of December.

Officials have said they are seeking a supply deal with the U.S. pharmaceutical giant, which has already committed hundreds of millions of doses this year to several wealthy nations.

The provisional approval calendar also shows the WHO is expected to approve Moderna's COVID-19 vaccine at the end of February.

Both Pfizer's and Moderna's vaccines have been authorized for emergency use in many Western countries, including the U.S. and some of the European countries. 

Another COVID-19 vaccine developed by the U.S.'s Johnson & Johnson, which has a non-binding agreement to supply COVAX with 500 million doses over an unspecified time-frame, is expected to get the WHO approval in May or June at the earliest, the WHO document says.

The COVID-19 vaccine developed by AstraZeneca with Oxford University and manufactured by the Serum Institute of India (SII) could be authorized by the WHO in January or February. The same vaccine produced in South Korea by SK Bioscience could be approved by the UN agency in the second half of February, at the earliest, the document shows.

(With input from Reuters)