Tens of thousands of people have taken to the streets across Brazil to protest against the government of President Jair Bolsonaro and its handling of the Covid pandemic.
The protests were triggered by recent allegations of corruption involving the purchase of vaccines by the health ministry.
Last month, the number of Covid-19 deaths in Brazil passed 500,000.
It is the second-highest death toll in the world after the US.
Late on Friday, a Supreme Court judge approved a request by the prosecutor general to open an investigation into Mr Bolsonaro’s role in the scandal.
Mr Bolsonaro has been accused by a whistleblower in the ministry of failing to take action when warned three months ago that senior officials had agreed to take bribes to purchase overpriced doses of an Indian-made vaccine, Covaxin.
He denies wrongdoing, saying the opposition is fabricating accusations to open impeachment proceedings against him.
President Bolsonaro has been heavily criticised for not implementing a co-ordinated national response and for his scepticism toward vaccines, lockdowns and mask-wearing requirements, which he has sought to loosen.
The health institute Fiocruz recently said the situation was “critical” in a country where only 11% of adults are fully vaccinated.
Last month, restaurants, bars and shops in many cities reopened, and many people in the streets do not wear face masks or follow social distancing.