The number of deaths related to Covid-19 has passed 500,000 in Brazil, the second-highest in the world, as experts say the outbreak could worsen amid slow vaccination and the start of winter.
The virus continues to spread as President Jair Bolsonaro refuses to back measures like social distancing.
The health institute Fiocruz says the situation is "critical". Only 11% of adults are fully vaccinated.
Tens of thousands of Brazilians joined anti-government protests on Saturday.
President Bolsonaro has been heavily criticised for not implementing a co-ordinated national response and for his scepticism toward vaccines, lockdowns and mask-wearing requirements, which he has sought to loosen.
The country has reported, on average, 70,000 cases and 2,000 deaths daily in the past week. Most of the new infections and deaths were among people aged 20-59, Fiocruz said, warning that the start of winter in the southern hemisphere, next week, could result in more infections.
Despite this, governors and mayors have already relaxed the restrictions imposed to curb the spread of the virus. In many cities, restaurants, bars and shops have reopened while many people in the streets do not wear face masks or follow social distancing.
"People in Brazil are tired and they normalise death now so I think we still have a long way to go," Dr Natalia Pasternak Taschner, a microbiologist at the Question of Science Institute, told the BBC.
"If we're not successful in changing the behaviour of people and if we don't have campaigns for mask wearing, social distancing and vaccinations coming directly from the central government we're not going to be able to control it."
On Saturday, protests against President Bolsonaro were held in cities across the country, with demonstrators accusing him of delaying the purchase of vaccines while prioritising unproven treatments, such as hydroxychloroquine.
In rallies in Rio de Janeiro, Brasília and elsewhere, furious Brazilians carried banners with slogans like "Bolsonaro must go" or simply "500,000".
"His position on Covid and his denialism are absurd. He has abandoned reality and common sense. There is no explaining this, it is surreal," Robert Almeida, a 50-year-old marching in Rio, told AFP.
Protester Denise Azevedo told Reuters: "Herd immunity won't do any good. The only immunity you can get is with the vaccine. There is no early treatment. I have lost many friends, almost lost a cousin... people are orphans, fatherless, motherless, and childless."
The outbreak in Brazil has been fuelled by more transmissible variants of the virus, including the one first identified in the Amazon region and now known as Gamma. The rate of occupancy of intensive care unit beds remains at or above 80% in most states, while cities struggle with short supplies of vaccines.
A parliamentary inquiry at the Brazilian Senate is looking into President Bolsonaro's handling of the pandemic. The opposition accuses him of delaying vaccine orders for political reasons, as he has consistently played down the severity of the pandemic.
But the president, whose popularity has plummeted, says he has done all he can to buy vaccines from several countries. He also insists the impact of lockdowns on the economy would be worse than the virus, a position shared by his supporters.
President Bolsonaro has not commented on the 500,000 deaths. On Twitter, Health Minister Marcelo Queiroga expressed solidarity with the "fathers, mothers, friends and relatives" of those who had died.
Only the US has reported more total deaths related to Covid-19.