Brazil halts trials of Chinese Covid vaccine

Brasilia: Brazil's health regulator said it had suspended clinical trials of a Chinese-developed COVID-19 vaccine after an "adverse incident" involving a volunteer recipient, a blow for one of the most advanced vaccine candidates.

The setback for CoronaVac, developed by China's Sinovac Biotech, came on Monday as US pharmaceutical giant Pfizer said its own vaccine candidate had shown 90 percent effectiveness -- sending global markets soaring and raising hopes of an end to the pandemic.

Sinovac Biotech on Tuesday stood by its creation, saying: "We are confident in the safety of the vaccine".

The Brazilian regulator Anvisa said it had "ruled to interrupt the clinical study of the CoronaVac vaccine after a serious adverse incident" involving a volunteer recipient on October 29.

It said it could not give details on what happened because of privacy regulations, but that such incidents included death, potentially fatal side effects, serious disability, hospitalization, birth defects and other "clinically significant events." Sinovac, however, said the incident was "not related to the vaccine", adding it will "continue to communicate with Brazil on this matter."

The public health center coordinating the trials of the vaccine in Brazil, the Butantan Institute, said it was "surprised" by Anvisa's decision.

The institute "is investigating in detail what happened," and "is at the Brazilian regulatory agency's disposal to provide any clarification necessary on any adverse incident the clinical trials may have presented," it said.

CoronaVac has been caught up in a messy political battle in Brazil, where its most visible backer has been Sao Paulo Governor Joao Doria, a top opponent of far-right President Jair Bolsonaro.