Brazil registered more than 4,000 COVID-19 deaths in 24 hours for the first time Tuesday, the health ministry said, as the country reeled from a surge of infections that has made it the current epicentre of the pandemic.

The coronavirus claimed 4,195 lives in the deadliest day of the pandemic yet for the hard-hit country, whose total reported death toll is now nearly 337,000, second only to the United States.

Brazil’s health system is buckling under the strain of the latest virus wave, which has forced doctors into agonizing decisions over which patients to give life-saving care and led cemeteries to hold night time burials to deal with the crush of coffins.

Experts say the surge is partly caused by a local variant of the virus known as P1 that can re-infect people who have had the original strain and is believed to be more contagious.

The country of 212 million people has registered an average of 2,757 COVID-19 deaths per day over the past week, the highest by far worldwide.