By Samantha Pearson and Luciana Magalhaes

Brazil began its Covid-19 vaccine rollout Sunday with the shot developed by China's Sinovac, minutes after its approval by regulators, promising to bring relief to a country that is struggling to cope with a surge in infections.

The country's health regulator, Anvisa, approved emergency use of the Chinese vaccine, known as CoronaVac, as well as the shot developed by AstraZeneca PLC and Oxford University.

The ruling follows a bitter tug of war between President Jair Bolsonaro and São Paulo's powerful state governor, João Doria, to secure the first vaccines for the country of more than 210 million people.

Gov. Doria, who is expected to run for president next year, has led a partnership with Chinese company Sinovac Biotech Ltd. to test and produce CoronaVac in São Paulo, criticizing what he has called a "genocidal" lack of action by Mr. Bolsonaro.

The dispute comes as the country's average daily death toll approaches 1,000 people, with scientists warning that a new variant that likely emerged in the Amazon could be partly responsible for a recent surge in infections. For the past week, Brazil has registered an average of more than 50,000 new cases of the disease each day -- the highest since the coronavirus pandemic began.

More than 200,000 people have died from Covid-19 in Brazil so far, the highest number of deaths reported anywhere outside the U.S.

"This is a triumph for science, a triumph against the deniers, against those who prefer the smell of death over the value and joy of life," Gov. Doria said. A former television star and businessman, he broke down into tears as the first Brazilian, a female nurse, was vaccinated during a news conference Sunday in São Paulo.

Anvisa's decision comes after the regulator on Saturday rejected an initial request by pharmaceutical company União Química for emergency use of the Russian Sputnik V coronavirus vaccine, saying the laboratory didn't meet the minimum requirements.

After importing 10.8 million doses of CoronaVac from China, São Paulo's government said it would continue to roll out the vaccine among health workers across Brazil's richest and most populous state over the next few days. The Butantan Institute, a São Paulo-based public institute that carried out late-stage trials of CoronaVac, is also in the process of producing an additional 46 million doses in Brazil.

With an efficacy rate just above 50%, CoronaVac is one of the weakest Covid-19 vaccines under development but it still works better than many flu vaccines and can be stored in an ordinary refrigerator, making it cheaper and easier to transport in poorer regions, infectious-disease specialists said.

Meanwhile, President Bolsonaro, a populist ex-army captain, has spent much of the past year dismissing Covid-19 as nothing more than a "little flu" and urging Brazilians to ignore the lockdown measures imposed by state governments and get back to work.

A fierce critic of China and Gov. Doria, Mr. Bolsonaro has also sought to discredit CoronaVac, warning his supporters it could disable or even kill them, without offering evidence.

Mr. Bolsonaro barred his health minister Eduardo Pazuello last year from buying CoronaVac for national use, betting instead on the AstraZeneca-Oxford shot. But after the development of the latter hit delays, the ministry said this month it would buy as many as 100 million doses of CoronaVac. Meanwhile, the federal government is still struggling to import doses of the AstraZeneca-Oxford shot via distributors in India.

As São Paulo rolled out its first vaccines on Sunday, Mr. Pazuello gave a televised statement, telling Brazilians that the federal government already had CoronaVac shots in its possession, saying Mr. Bolsonaro's administration had paid for them. Gov. Doria said this information wasn't true, saying his state hadn't received federal money for the vaccine. Gov. Doria said he had authorized its distribution only on Sunday, posting photos to Twitter of refrigerated trucks loaded with vaccines ready to depart and urging the federal government to administer them as fast as possible.

Sunday's announcement was a rare piece of good news in a country that has been battered with tales of spiraling deaths and political infighting since the pandemic began. "It's about time!" said Victor Belinatti, a 23-year-old graphic designer from São Paulo, saying he agreed with the distribution of the vaccine to the rest of the country. "So many states are facing difficulties...we have to be fair."

The political battle over vaccines comes as the health systems of states such as Rio de Janeiro and Amazonas in the Amazon rainforest verge on the edge of collapse.

Relatives of critically ill patients in Manaus, one of the biggest cities in the Amazon, have resorted to buying their own oxygen canisters as supplies run out across the state.

The lives of more than 60 premature babies in need of oxygen are also at risk, Amazonas's government said Friday, warning it would have to transfer them to other states to keep them alive. The health ministry said late Friday that it was sending enough oxygen to support them for another 48 hours.

Venezuela's foreign minister, Jorge Arreaza, said Saturday that trucks carrying "thousands of liters of oxygen" were also on their way to Manaus from Puerto Ordaz, a 26-hour drive north through the rainforest.

For Mr. Bolsonaro, a staunch conservative and critic of China's Communist Party and Venezuela's socialist regime, this weekend's events are likely to erode his popularity, political scientists said.

Mr. Bolsonaro, who is facing dozens of impeachment requests from opposition parties, has remained popular throughout the pandemic, in part because of generous handouts to the poor last year. However, with the payments now stopped, Mr. Bolsonaro will face increasing pressure, said Rafael Cortez, a political scientist at São Paulo-based consulting firm Tendências.

"All this talk of impeachment should further weaken the government and its relationship with Congress," Mr. Cortez said. "It's going to be a difficult year for Brazil and for Bolsonaro."

Write to Samantha Pearson at samantha.pearson@wsj.com and Luciana Magalhaes at Luciana.Magalhaes@wsj.com

(END) Dow Jones Newswires

01-17-21 1801ET