Brazil's death toll from Covid-19 is expected to pass 500,000 as experts warn that the world's second deadliest outbreak may worsen due to delayed vaccinations and the government's refusal to back social distancing measures.

Only 11 per cent of Brazilians have been fully vaccinated and epidemiologists warn that, with winter arriving in the southern hemisphere and new variants of the coronavirus circulating, deaths will continue to mount even if immunisations gain steam, Reuters reports.

Brazil has registered 498,499 deaths from 17,801,462 confirmed Covid-19 cases, according to Health Ministry data on Friday, the worst official death toll outside the United States.

Over the past week, Brazil has averaged 2,000 deaths per day.