RIO DE JANEIRO (AFP) - Brazil on Saturday (June 19) became the second country after the United States to surpass 500,000 Covid-19 deaths as the South American giant grapples with a third wave of the pandemic.

Health Minister Marcelo Queiroga tweeted: "500,000 lives lost due to the pandemic that affects our Brazil and the world."

The Health Ministry reported 500,800 deaths, including 2,301 in the last 24 hours, a toll that many experts say is an underestimation of the health crisis.

Last week, the average number of daily deaths surpassed 2,000 for the first time since May 10.

"The third wave is arriving, there's already a change in the case and death curves," Dr Ethel Maciel, an epidemiologist from Espirito Santo University said.

"Our vaccination (programme), which could make a difference, is slow and there are no signs of restrictive measures, quite the contrary."

In large cities, life seems almost back to normal with restaurants, bars and shops open and many people in the streets not wearing face masks.

Yet the situation is critical in 19 of Brazil's 27 states with more than 80 per cent occupancy of intensive care beds - in nine of those states it is more than 90 per cent.

The second wave, from January to April this year, was particularly deadly.

The number of deaths increased exponentially with the arrival of the Gamma virus variant that originated in Manaus, in the north of Brazil.

The number of deaths gradually began to fall last month, thanks in part to the closure of businesses when the pandemic was at its worst.

But many epidemiologists believe lockdown restrictions were lifted too soon at a time when daily deaths were still up at around the 2,000 mark.

Contrary to what has been seen in Europe, there has been no real trough between the different waves in Brazil.

"I don't know if it's a third wave... it seems we never got out of the first one," said Dr Alexandre da Silva, a specialist in public health at the University of Sao Paulo.

"It seems the pandemic has now turned into a marathon runner who is pacing his race. It's not a sprinter who does his sprint but then loses power."

Brazil has recently received several batches of vaccines, including from US pharmaceutical giant Pfizer, but the country has managed to fully vaccinate only 11 per cent of the population, with 29 per cent receiving one dose.

The vaccination drive began late in mid-January with AstraZeneca and CoronaVac jabs.

Far-right President Jair Bolsonaro, who previously hit out at vaccines, has promised to immunise the entire population by the end of the year - something specialists consider unlikely.

Mr Bolsonaro has been criticised for downplaying the pandemic from the outset, opposing lockdown measures and plugging unproven medical treatments for Covid-19. On Saturday, thousands of Brazilians again took to the streets in protest against him.

In rallies in Rio de Janeiro, Brasilia and elsewhere, people carried banners with slogans like "Bolsonaro must go" or simply "500,000".

"His position on Covid-19 and his denialism are absurd. He has abandoned reality and common sense. There is no explaining this, it is surreal," said Mr Robert Almeida, a 50-year-old photographer marching in Rio.

Leftist former president Luiz Inacio Lula da Silva tweeted: "500,000 deaths from a disease for which there is now a vaccine, in a country that has been a world leader in vaccination. There is a word for that: genocide.

"Solidarity with the people of Brazil."

It was all the more surprising, then, that Brazil agreed at the 11th hour to host the Copa America football tournament, seeing global stars such as Argentina's Lionel Messi, Luis Suarez of Uruguay and the host's own Neymar arrive from European clubs.

The matches are being played behind closed doors, but Mr Bolsonaro has come under fire for giving his blessings to host the tournament in the midst of a pandemic when both Argentina and Colombia had to pull out.

Many Brazilians have voiced their opposition against the tournament.

Beyond the football tournament, Dr Maciel has said the government's pandemic management is responsible for thousands of extra deaths.

"If we had acted in a different and coordinated way, giving concrete information to the people on public health measures... none of this would have happened," she said.

She accused the government of "confusing the people" by advising against health measures backed by science, such as social distancing and the use of face masks.

Mr Bolsonaro shows no signs of changing tack, though, and earlier this month announced he would ask the health minister to lift the requirement to wear masks outdoors.

He has already been hit with several fines by the local authorities for holding rallies without wearing a mask.

Mr Bolsonaro is also under investigation by the Senate over his chaotic pandemic management.