SAO PAULO (AP) — A vaccine candidate made by China’s Sinovac is 78% effective in protecting against COVID-19, according to results of a study announced Thursday by Brazilian state health officials seeking federal approval of the shot.

More than 12,000 health workers participated in the study, which detected 218 cases of COVID-19 — about 160 of those among people who received a placebo rather than the actual vaccine.

Turkish officials last month said that a smaller, companion study in that country of the same vaccine candidate found an efficacy rate of over 90%.

The government of Sao Paulo state, which has contracted for the vaccine, said it is asking Brazil's federal health regulators for emergency approval to begin using it. Gov. João Doria plans to start a vaccination campaign for the state's 46 million residents on Jan. 25.

Sao Paulo's Butantan Institute, which is Sinovac's partner in Brazil, did not disclose data such as results by age and gender or the number of asymptomatic volunteers in the sample, which many epidemiologists require to assess whether the shot complies with safety standards.

Officials said details will be published after Brazil’s health regulatory agency approves the vaccine. They gave no date for disclosure in scientific publications.

Gonzalo Vecina, one of the founders of Brazil's health agency, said the data revealed so far is reassuring enough to approve the shot for emergency use.

“In a general picture, we do have sufficient information to move on to register and use it,” Vecina told The Associated Press. “We need 320 million vaccines for 160 million Brazilians, that's our population above 18 years of age. If the federal government doesn't do it, the state governments will, but we have to do it fast. We are already behind a lot of nations.”

The health agency said in a statement that it has not yet received full data on the study.

The researchers reported no serious side effects in the study.

The U.S. has required vaccine candidates to be tested in at least 30,000 people to determine safety and effectiveness.

The Sinovac candidate was ready for late-stage testing at a time when China had such little coronavirus spread that the company was forced to look to multiple locations abroad to amass the necessary data.

“Today is the day of hope, the day of life,” Doria said in a news conference. Brazil is nearing 200,000 deaths caused by the virus.

The Sao Paulo governor is an adversary of President Jair Bolsonaro, who has downplayed the risks of the pandemic since the beginning and has repeatedly questioned the quality of the Chinese vaccine.

After Doria's announcement, Brazil's health minister, Eduardo Pazuello, said at a news conference in Brasilia that the Bolsonaro administration would buy up to 100 million doses of the Sinovac shot.

“These shots will be distributed equally and proportionally among all states, as will happen to the AstraZeneca ones,” Pazuello said. Brazil’s federal government has a deal to secure up to 100 million doses of the vaccine created by AstraZeneca, 70 million of them produced in home soil.

Doria told TV Globo that the deal announced by Pazuello was yet to be concluded. He did not change his plans to start vaccination in Brazil's wealthiest and most populous state on Jan. 25.

Earlier on Thursday, Bolsonaro told supporters in capital Brasilia that vaccines approved for emergency use should not be mandatory, without naming the Sinovac shot. So far, his administration has no national vaccination plan.

“No one can force a person to take something whose consequences are yet unknown,” Bolsonaro said. The president, who earlier experienced a bout of COVID-19, repeated he will not take any vaccine.

A different Chinese company, SinoPharm, announced last week that its similar vaccine is about 79% effective. Both of those vaccines rely on inactivated viruses.