Brazil’s health minister, Marcelo Queiroga, has tested positive for Covid and gone into isolation, 24 hours after meeting a maskless Boris Johnson and other British officials in New York.

Queiroga, who sat close to Johnson and the foreign secretary, Liz Truss, on Monday during their meeting with Brazil’s president, Jair Bolsonaro, announced his positive test on Twitter on Tuesday night.

Soon after, the Brazilian news website Metropoles reported that Brazil had decided to abort its participation in the UN general assembly as a result of what was the second confirmed case of Covid in its delegation.

Queiroga, 55, a cardiologist, was filmed shaking hands with Johnson and patting the prime minister on the arm during Monday’s gathering at the consulate general’s house in New York.

Despite the fact Bolsonaro publicly claims not to have been vaccinated against Covid, Johnson, Truss and other members of the British delegation were not wearing masks for the encounter, although Queiroga, who sat opposite the British politicians on a sofa, did use one.

Hours after the meeting, Queiroga was caught on camera making obscene hand gestures to Brazilian protesters who had taken to the streets of New York to denounce Bolsonaro’s anti-science handling of the Covid outbreak, which has killed nearly 600,000 Brazilians.

The following day Queiroga, who was reportedly staying at the same hotel as the US president, Joe Biden, was at the UN headquarters for the opening session of its general assembly. He reportedly took part in meetings with the UN secretary general, Antonio Guterres, and Poland’s president, Andrzej Duda.

Queiroga was vaccinated against Covid in January, two months before being made health minister, and shared a video of the moment on Twitter.

Other members of Bolsonaro’s cabinet have been more discreet about getting their shots. In April one senior minister, Luiz Eduardo Ramos, claimed he had snuck off to a shopping mall in the capital, Brasilia, to be jabbed, apparently in order to avoid offending the president.

In a leaked video message, Ramos said: “Like any human being, I want to live. I have two wonderful grandkids, a beautiful wife, I still have dreams. So I want to carry on living.”

Bolsonaro, who has dismissed Covid as a “little flu”, used his speech to the UN assembly to attack lockdown and isolation measures, which he falsely claimed caused inflation, and to tout ineffective and potentially harmful coronavirus “remedies”, known in Brazil as “early treatment”.

“We do not understand why many countries – along with a large part of the media – opposed ‘early treatment’,” Brazil’s far-right leader told world leaders, announcing that he himself had taken such drugs, which include the antimalarial hydroxychloroquine and the antiparasitic ivermectin.

Bolsonaro’s former health minister Luiz Henrique Mandetta goaded Queiroga after his announcement on Tuesday, asking: “Is he going to undergo ‘early treatment’?”

After meeting Queiroga and Bolsonaro, Johnson travelled to Washington to meet Biden on Tuesday. Pictures showed both leaders wearing masks for that encounter in the Oval Office of the White House.