The World Health Organization said on June 1 that it approved the COVID-19 vaccine from Sinovac Biotech for emergency use.

Deutsche Welle (DW) says it is the second Chinese vaccine to make the list, after the shot from Sinopharm was approved in April. The WHO approved list includes vaccines developed by BioNTech-Pfizer, Moderna, AstraZeneca and Johnson & Johnson.

The announcement reportedly allows the two-dose vaccine to be used as part of the COVAX program, which provides vaccines to many low-income nations.  Only the AstraZeneca and BioNTech-Pfizer jabs are currently going through the COVAX scheme.

There is no currently confirmed deal for Sinovac doses to be used under the COVAX program, according to DW.

WHO Director-General Tedros Adhanom Ghebreyesus said the vaccine was safe and effective, and its easy storage requirements made it suitable for harsh climates.

The jab's efficacy has reportedly varied widely in different trials. The WHO's separate Strategic Advisory Group of Experts (SAGE) showed the vaccine efficacy in phase III trials ranged from 51% to 84%.  The WHO said the shot prevented severe COVID-19 and hospitalization in 100% of the tested population.

"WHO recommends the vaccine for use in adults 18 years and older, in a two-dose schedule with a spacing of two to four weeks," the UN health agency said in its statement. 

The organization said that because there were few people over 60 in the trials, they could not estimate how well it would perform on the elderly population.