The Covid-19 vaccine produced by China's Sinovac Biotech is efficacious in preventing Covid-19 in adults under 60, but some quality data on the risk of serious adverse effects is lacking, World Health Organization experts have found.

The independent experts on the WHO's Strategic Advisory Group of Experts (Sage) reviewed Sinovac's CoronaVac jab from phase 3 clinical trials in China, Brazil, Indonesia, Turkey and Chile.