Guterres, 72, has canceled his upcoming in-person engagements, sources told AFP.
The UN chief was due to be the guest of honor of the UN Press Association at its annual gala in Manhattan on Wednesday. On Thursday, he was to participate in a UN Security Council meeting on the challenges of terrorism and climate change, led by Niger’s President Mohamed Bazoum.
Bazoum, whose country currently holds the council presidency, arrived in New York on Tuesday and is expected to stay until the end of the week, when he heads to Washington.
The spokesman for the secretary-general, Stephane Dujarric, declined to comment immediately on Guterres’s condition.
Dujarric indicated a few days ago that Guterres had recently received his third dose of the anti-coronavirus vaccine, after having hesitated for a long time about the advisability of receiving booster shots while millions of people throughout the world have yet to receive their first jab.
Brazil on Tuesday ruled out requiring a COVID-19 vaccination certificate for foreign travelers arriving in the country, despite a recommendation from the national health regulator.
The move came after far-right President Jair Bolsonaro compared such a mandate to a “leash” for animals.
Health Minister Marcelo Queiroga told reporters after a meeting at the presidency that “people cannot be discriminated between vaccinated and unvaccinated to impose restrictions.”
However, Queiroga said that with the precise characteristics of the Omicron variant still unknown, Brazil will require “a five-day quarantine” for unvaccinated travelers, as recommended by the health regulator Anvisa.
After that period, and with a negative PCR test, foreigners traveling to the country as tourists “can take advantage of the beauties of our great Brazil,” the minister said.
Until now, the only requirement had been to present a negative PCR test.
“Sometimes it is better to lose your life than to lose your freedom,” Queiroga added, echoing Bolsonaro’s own previous statements.
Ahead of the announcement, Bolsonaro, who has not been vaccinated, rejected Anvisa’s request for a health passport.
“We asked, why the health passport? What is that leash that they want to put on the Brazilian people? Where is our freedom? I would rather die than lose my freedom,” the former army officer said.
Brazil has suffered more than 615,000 COVID deaths since the start of the pandemic, second only to the United States in absolute numbers.