The World Health Organization on Tuesday approved the Chinese Sinovac Covid-19 vaccine for emergency use.

The UN health agency signed off on the Beijing-based firm Sinovac's two-dose vaccine CoronaVac, which is already being used in several countries around the world.

The WHO said the emergency use listing (EUL) gives assurance that the vaccine has met international standards.

Last month Sinopharm became the first Chinese vaccine to be approved by the WHO.

"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 agency said in a statement.

"Vaccine efficacy results showed that the vaccine prevented symptomatic disease in 51% of those vaccinated and prevented severe Covid-19 and hospitalisation in 100% of the studied population."

Few people aged over 60 took part in the clinical trial of Sinovac's jab.

However, the WHO said there should be no upper age limit on the vaccine as there is "no reason to believe it has a different safety profile" in older generations.