vaccine developed by China's Sinovac Biotech appeared to be safe in a late-stage clinical trial in Brazil, preliminary results showed on Monday.São Paulo's Butantan Institute, one of Brazil's leading biomedical research centers, which is carrying out the Phase 3 tests, said the two-dose vaccine, called CoronaVac, proved to be safe in a trial so far involving 9,000 volunteers.But Butantan director Dimas Covas said data on how effective the vaccine is will not be released until the trial is completed on all of the 13,000 volunteers."The first results of the clinical study conducted in Brazil prove that among all the vaccines tested in the country, CoronaVac is the safest, the one with the best and most promising rates," São Paulo Governor.