Brazil on Tuesday registered the highest daily number of Covid deaths since the pandemic started.

The health ministry said 1,641 people had died with Covid in the previous 24 hours.

The record was reached as scientists said that a new variant first found in Brazil appears more contagious.

Brazil, where more than a quarter of a million people have died with Covid, has the second highest coronavirus death toll after the United States.

What's the situation in Brazil?

Across the country, there have been more than 10.5 million confirmed cases of coronavirus. Only the US and India have registered more.

The pandemic spread quickly after first arriving in Brazil and reached a first peak at the end of July, when daily new cases were above 70,000 and daily deaths above 1,500.

Cases and deaths across Brazil fell until early November before a second wave saw cases rise again, a rise which appears to have further accelerated since January.

What's behind the new spike?

Researchers from the University of São Paulo working with their colleagues at Imperial College London and Oxford University think that the second wave may be linked to the emergence of a new variant of coronavirus which has been traced to the city of Manaus.

Manaus, in the Amazon region, was one of the hardest hit cities in the first wave of the pandemic.

One study of blood donors suggested that three quarters of the city's population had been infected with Covid by October.

It was expected that the people infected in the first wave would have acquired some degree of protection or immunity. And yet, the city has seen a second wave of infections.

The researchers think this may be because a new variant has emerged which may be evading immunity provided by past infections.

What's known about the new variant?

The new variant, named P.1, was first detected in people who had travelled from Manaus to Japan in January.

The researchers studying it think it first emerged in Manaus in early November and has been spreading there quickly since.

They say that that genomic sequencing found that this second wave in Manaus "was associated with the emergence and rapid spread" of the P.1 variant.

Their data - which is still preliminary - suggests that the P.1 variant could be up to twice as transmittable as the original version of the virus.

It also suggests that the new variant could evade immunity built up by having had the original version of Covid.

They put the chance of reinfection at between 25% and 60%.

What about vaccines?

Brazil, the worst-affected country by Covid in Latin America, has lagged behind in its roll-out of Covid vaccines.

A nurse in São Paulo became the first person to be vaccinated on 17 January, three weeks after Chile, Mexico and Costa Rica had already started their vaccination campaigns.

Vaccinating its population of 211 million living across a huge territory was always going to be a challenge, but delays in the delivery of the vaccine and the lack of a co-ordinated nationwide approach produced further slowdowns.

A tally kept by Brazilian media organisations based on data provided by state health authorities suggests 7.1 million people have so far received at least one dose. That amounts to 3.4% of the population.

Frustrated state governors announced on Tuesday that they would join forces to buy vaccines directly from manufacturers rather than wait for the federal government to deliver them.

They have criticised President Jair Bolsonaro, who has belittled the risks posed by the virus from the start of the pandemic, for not securing adequate vaccine supplies.

The governor of São Paulo state, João Doria, has been particularly scathing of President Bolsonaro's handling of the pandemic.