Brazil’s far-right president, Jair Bolsonaro, is facing an intensifying public backlash after his muddled reaction to the coronavirus crisis sparked five successive nights of protests and predictions that his political authority had sustained a potentially fatal blow.

Brazil has recorded 1,128 coronavirus cases and 18 deaths, with the country’s health minister last week saying the public health system was likely to collapse by the end of April.

But Bolsonaro has continued to downplay the pandemic, despite more than 20 members of a delegation he recently led to the US becoming infected with Covid-19.

In an interview on Saturday, he criticised efforts to contain the virus through large-scale quarantines or shutdowns and described the governors of states including Rio de Janeiro and São Paulo as “irresponsible”, saying they were creating a “climate of terror” by doing so.

“It’s an excessive dose of medicine – and too much medicine becomes poison,” Bolsonaro said, rejecting criticism of his administration’s response. “I’m the manager of the team and the team is playing very well, thank God.”

A growing number of Brazil’s 209 million citizens appear to disagree.

Since last Tuesday, cities across the country have witnessed nightly panelaço (pan-banging) protests where dissenters express their dissatisfaction with Bolsonaro by pummelling saucepans from windows and balconies.

Much of the fury has focused on Bolsonaro’s decision to pose for triumphant photographs and mingle with supporters outside the presidential palace last Sunday despite receiving medical advice to self-quarantine because of his possible exposure to the virus during a trip to meet Donald Trump in the US.

Since then, Bolsonaro has come under heavy fire from Brazilian media and political opponents for what they call his reckless and inept behaviour.

On Friday, the conservative Estado de São Paulo newspaper said: “Scientists around the world are fighting to find a treatment for Covid-19. In Brazil, meanwhile, the current government’s incompetence is found to be incurable.”

The news magazine Istoé labelled Bolsonaro an “irresponsible ignoramus”. Writing in the same magazine, Carlos José Marques lamented how Brazil’s presidency was now defined by “moral, intellectual and administrative delinquency”.

“You don’t need a medical council to quickly attest the uselessness of this country’s leader,” the journalist wrote.

Even former allies have turned on Brazil’s president, with Janaina Paschoal, a rightwing congresswoman once touted as Bolsonaro’s vice-presidential running mate, calling for an end to his presidency. “We are being invaded by an invisible enemy. We need people who are capable of leading the nation,” she said.

Bolsonaro swept to power in 2018, casting himself as a Trump-style outsider who could rescue Brazil from what he called “years of leftist villainy”.

Opinion polls showed Bolsonaro’s support slumping throughout 2019, his first year in office, thanks to a lifeless economy and a series of bizarre and offensive gaffes including sharing a pornographic video with millions of Twitter followers and mocking Brigitte Macron, France’s first lady.

But many observers believe his recent moves – which include dismissing coronavirus as media “hysteria” and failing to prevent his politician son from picking a diplomatic fight with China – will inflict profound damage.

“I find it very hard to imagine how Bolsonaro could recover from this,” said Oliver Stuenkel, an international relations professor at the Fundação Getúlio Vargas in São Paulo.

“Bolsonaro is very fragile already and I feel like the pandemic has just made it clear to many people that he will not be able to lead Brazil through this in any satisfactory way.

“Even if he suddenly says: ‘OK guys – I get it,’ it will be very hard for people not to blame him directly for what will happen – and I think it’s very hard to imagine that this will not be terrible for Brazil.”

Bruno Boghossian, a columnist for the Folha de São Paulo newspaper in the capital, Brasília, said this week’s pot-banging protests had been highly symbolic rather than huge in scale.

But, strikingly, they had taken place in wealthy areas that overwhelmingly backed Bolsonaro in 2018 because of anger with the left.

It was unclear how severely Bolsonaro’s political standing had been shaken. “I can’t tell you if … his popularity is going to collapse in one fell swoop,” Boghossian said.

“But I think damage has already been done because people will remember – now and forever – how the president behaved as the seriousness of this [pandemic] became clear in Brazil.”

Boghossian said Bolsonaro had long believed his presidency was “bullet-proofed” by expectations that Brazil’s economy would improve under his administration. “The problem is that economic meltdown is [now] inevitable,” he said.