A nurse has received Brazil's first Covid-19 vaccine dose after regulators gave emergency approval to two jabs.
Regulator Anvisa gave the green light to vaccines from Oxford-AstraZeneca and China's Sinovac, doses of which will be distributed among all 27 states.
Brazil has the world's second-highest death toll from Covid-19 and cases are rising again across the country.
President Jair Bolsonaro has been heavily criticised for his handling of the pandemic.
The far-right leader has played down the pandemic from the beginning, promoted an unproven treatment for the disease and gone against measures including mask-wearing and social distancing.
The president, who caught Covid-19 last year and recovered, has said he will not take a vaccine.
Authorities reported 551 new fatalities on Sunday, the first time in six days that it had fallen short of 1,000 although this could reflect a delay in the reporting of numbers over the weekend.
In all, more than 209,000 Covid-related deaths have been recorded in Brazil, a raw total figure only exceeded by the US.
Over 8.4 million infections have been confirmed since the start of the pandemic - the third-highest tally in the world.
Health Minister Eduardo Pazuello told reporters that the national vaccination programme in the country of 211 million people would begin in earnest in the coming days. Two Brazilian biomedical centres which have been given approval to produce the jabs will be heavily involved.
About six million doses of the Sinovac-developed CoronaVac have already been produced in Brazil, while the government is waiting for shipments of the AstraZeneca vaccine from a laboratory in India.
Shortly after Anvisa's board gave emergency approval, Monica Calazans, a 54-year-old nurse in São Paulo, became the first person to be inoculated with CoronaVac.
Her vaccination was organised by the São Paulo state government, which is led by Mr Bolsonaro's main political rival, João Doria.
A rare piece of good news
This has been a rare piece of good news today for Brazilians who are grappling with a devastating second wave.
From where I am, the city of Manaus, the vaccine does not feel real. People here are trying to recover a collapsed health system and doing what they can to keep their sick relatives alive.
The pandemic has become deeply political in Brazil. President Bolsonaro continues to present himself as a vaccine sceptic and he was notably absent as the vaccines were approved. Instead, Monday's newspapers will no doubt have São Paulo Governor Doria slapped on their front pages.
He is expected to run in next year's presidential elections and has backed the Sinovac vaccine from the very start. He was once a Bolsonaro ally and is now his nemesis - but there is no doubt who is leading the way in trying to get the population vaccinated.
Earlier this week researchers said the Chinese vaccine had been found to be 50.4% effective in Brazilian clinical trials. This, results showed, was significantly less effective than previous data suggested - barely over the 50% needed for regulatory approval.
CoronaVac is also being used in China, Indonesia and Turkey.
The news comes after revelations that a new coronavirus variant has emerged in Brazil. Several cases were traced back to the Amazonas state, where a state of emergency is in place.
Manaus, the state capital, has been hit especially hard, with beds and life-saving oxygen running low. Refrigerated containers have also been brought to hospitals to help store bodies.
Neighbouring Venezuela said it had sent a convoy of trucks with oxygen supplies to help Amazonas.
President Bolsonaro has faced mounting criticism for his handling of Brazil's outbreak, and several anti-government protests were held last week.
An opponent of lockdowns, he has previously blamed state governors and mayors for the Covid crisis, saying the federal government has provided all the resources needed to tackle the virus.