CoronaVac, produced by the Chinese private laboratory Sinovac is currently undergoing phase 3 clinical trials in Sao Paulo.

The health regulator in a statement noted that while the vaccine has had an emergency use authorization in China since June, the country’s authorities have not been transparent about the criteria used for granting this authorization. Brazilian President Jair Bolsonaro has repeatedly cast doubt on the CoronaVac vaccine.

Sao Paulo Governor Joao Doria said the state expected to start vaccinating its residents in January, though Brazil’s most populous state will not be able to use CoronaVac until it is approved by Anvisa. China’s foreign ministry spokesman Wang Wenbin defended Coronavac’s development process, saying some countries had approved Chinese inoculations and termed it as a demonstration of the safety and effectiveness of China's vaccines.

As per reports, tens of thousands of people have taken the Sinovac vaccine in China’s emergency-use program that was approved for limited groups of high-risk category people.

Little information is publicly available about the approval process, scope, size, and scientific merit of the emergency-use program. Experts have raised concerns about safety and efficacy, both from a legal as well as ethical standpoint.

China has defended the use of experimental vaccines in this way saying the move was sanctioned by the World Health Organization (WHO).