Chinese-developed Covid-19 vaccine CoronaVac showed at least 78-percent effectiveness in final-stage clinical trials in Brazil, officials announced Thursday, saying they would apply for emergency approval from the Brazilian regulatory agency to begin a vaccination campaign.
"This is a historic day, a day of hope," Sao Paulo state Governor Joao Doria told a news conference announcing the results.
He said his state's vaccination campaign would begin on January 25, though that will require approval from federal regulatory agency Anvisa.
The Butantan Institute, Sao Paulo's leading public health center, said it would apply for emergency approval by Friday.
The vaccine, developed by Chinese pharmaceutical firm Sinovac, showed effectiveness of 78 percent in Phase 3 testing on 13,000 volunteers in the Brazilian study, officials said.
And no one who received it developed a severe case of Covid-19, Doria added.
Turkey, which also helped carry out Phase 3 tests of CoronaVac, said last month the vaccine had shown effectiveness of 91.25 percent in its trials.
Sinovac has not yet released worldwide results from the tests, which are also being carried out in Chile and Indonesia.
The company has faced criticism for not supplying full data sooner.
The efficacy rate reported by Brazil for CoronaVac is well below the 95 percent reported for the vaccines from US pharmaceutical firms Pfizer and Moderna.
However, CoronaVac is easier to deploy because it does not have to be stored at extremely low temperatures.
Brazil has the second-highest death toll in the pandemic, after the United States, with nearly 200,000 people killed.
CoronaVac has been caught up in a political battle between Doria and President Jair Bolsonaro, likely opponents in Brazil's 2022 presidential election.
Doria pushed for a deal to test and produce the vaccine in Brazil. But Bolsonaro, who says he does not plan to be vaccinated himself, has derided it as "Joao Doria's Chinese vaccine."