Brazilian officials on Thursday announced an agreement with China's Sinovac Biotech to produce its coronavirus vaccine in the state of Sao Paulo, where tests involving 9,000 volunteers are to begin next month.

Brazil has the world's second-highest coronavirus caseload after the United States, with more than 770,000 confirmed infections and nearly 40,000 deaths.

Sao Paulo governor Joao Doria told a news conference that the Butantan Institute, Brazil's leading research center, had reached a technology transfer agreement with Sinovac Biotech.

"The studies show that the vaccine could be distributed by June 2021," if tests prove conclusive, Doria said.

"This agreement would allow us to produce at large scale and immunize millions of Brazilians."

Sinovac Biotech, one of four Chinese laboratories authorized to conduct clinical vaccine trials, said a month ago that it was prepared to produce 100 million doses of the vaccine under the commercial name Coronavac.

Read more: China's coronavirus vaccine facility ready to make millions of doses

In Sao Paulo, 9,000 volunteers will be injected with doses of that vaccine beginning in mid-July, in the third and final phase of testing.

Last week, Sao Paulo State University announced that a vaccine being developed by the University of Oxford will be tested among 2,000 Brazilian volunteers beginning in mid-June.

In unveiling the deal, which he described as "historic," Doria criticized President Jair Bolsonaro.

"We have had to overcome Brazil's disagreements with China, with other countries and with organizations like the WHO," he said, referring to criticism of China by several of the country's cabinet ministers.

Bolsonaro in recent days has also threatened to withdraw Brazil from the World Health Organization -- as the United States did last month -- accusing it of "ideological bias."

Alluding to the controversy, Doria said, "The politicization of disease has never saved a life, to the contrary."

Since the onset of the pandemic, Bolsonaro has clashed with state governors over stay-at-home measures that they've adopted to prevent the spread of the virus.

He has continued to press for a resumption of economic activities even though infections continue to rise.