More than 300 Brazilians assembled in São Paulo's two biggest cities Sunday to protest state Gov. João Doria's push for compulsory COVID vaccination and testing of an experimental vaccine developed by China biotechnology company Sinovac.

Doria favors making COVID immunizations mandatory, as soon as vaccines are available, triggering a dispute with President Jair Bolsonaro who promises the vaccinations will be voluntary.

Bolsonaro has opposed the use of Sinovac's CoronaVac, saying Brazilians will not be lab rats for China. Brazil's chief justice said the supreme court would decide on the matter.

The issue has become a point in mayoral and city council elections later this month and, as most experts in the health and medical sector favor immunization, social media campaigns have raised doubts about the likely ill effects of the vaccine.

SinoVac is being tested in Brazil as part of the government's third stage clinical trials with backing from the Doria administration. The country's federal health officials last month disclosed they would procure 46 million doses of the Chinese vaccine, depending on regulatory approval, in a deal favored by state officials.

Brazil expects to have a COVID vaccine approved and ready for use in a national immunization program by June next year, Antonio Barra Torres, chief of the nation's health regulator Anvisa, said.

Anvisa said it remained fluid with its vaccine approval benchmarks, evaluating the risks of committing to an effectivity rate under 50%, CGTN reported.

Meanwhile, Brazil Health Minister Eduardo Pazuello was discharged from hospital Sunday after being diagnosed earlier with COVID, the ministry said in a statement. Pazuello tested positive for the virus Oct. 21.

Brazil has 5.5 million COVID cases with 4.98 million recoveries and 160,000 deaths.

Russia has agreed to supply the Brazil states of Bahia and Parana with its Sputnik V vaccine, but it must first be tested and approved by Anvisa.