A Brazilian hospital chain tested unproven drugs on elderly Covid-19 patients without their knowledge as part of an effort to validate President Jair Bolsonaro's preferred 'miracle cure,' a lawyer for whistleblowing doctors has told senators.

At least nine people died of Covid-19 during the trials at the Prevent Senior hospital chain from March to April 2020, but their charts were altered to hide the cause of death, lawyer Bruna Morato told a Senate inquiry.

Prevent Senior rejected the accusations as unfounded and said it had "rigorously reported" all deaths. It added in a statement that seven per cent of the 56,000 Covid-19 patients it treated had died, a better record than other public and private hospitals.

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