Positive Coronavirus Test for Trump Shocks Global Markets, Sets Off Reactions

The United Nations Office for Disaster Risk Reduction tweeted, “Nobody is immune from #COVID19.”

In Myanmar, a Baptist minister who met with Mr. Trump in the Oval Office last year and told him about oppression and torture by the military, said that having Covid-19 could help the president better understand the pain of others.

“There are many critics of Trump regarding Covid-19,” said the minister, Hkalam Samson. “Now he is suffering himself and he should be compassionate for his people by now.”

Others saw a degree of justice in his diagnosis, given his record of diminishing the threat of the virus, refusing simple precautions like wearing a mask and holding campaign rallies without little to no social distancing. During the presidential debate on Tuesday, he mocked former Vice President Joseph R. Biden Jr. for wearing a mask.

“When the president of the United States, the most powerful person in the world, can catch this, the virus has no boundaries,” said Wang Huiyao, the founder and president of the Center for China and Globalization, an influential research group in Beijing.

Mr. Wang said that the president’s positive test result might become a global reminder of the value of wearing face masks, which are still widely worn in mainland China even though it has not reported a locally transmitted case in more than six weeks.

“He has also had large crowds, shaking hands and greeting people, and he seldom wears a mask,” Mr. Wang said. “He probably serves as a good reminder to the whole world that, as U.S. experts have said, it is important to wear a mask.”

In China, the news sparked an online firestorm, and within an hour had rocketed to the top of the most-searched topics on Sina Weibo, a popular though heavily censored social media platform. The commentary reflected a mix of sympathy, disbelief and even glee from some online users who saw the development as just retribution for Mr. Trump, who is widely seen in China as having spearheaded the recent downward spiral in relations between the United States and China.