Covid-19 Live Updates: Moderna Is Working on Vaccine Booster for New Variant

statement on Monday. It is the first confirmed case of the variant in the United States.

The case was identified in a Minnesota resident who had recently traveled to Brazil, the department said, which could suggest that the variant may not yet be widely circulating.

But it was only a matter of time before the variant was detected in the United States, said Dr. Anthony S. Fauci, a Covid adviser to President Biden. “With the world travel that you have, and the degree of transmissibility efficiency, it’s not surprising,” he said.

The variant, known as B. or P.1, shares many …

AMLO, Mexican President, Has Coronavirus

Mexico’s president, Andrés Manuel López Obrador, said Sunday that he had contracted the coronavirus and was undergoing “medical treatment” for what he described as mild symptoms.

Mr. López Obrador, writing on Twitter, said he would continue to carry out his official duties, including holding a call with President Vladimir V. Putin of Russia that is set for Monday.

“As always, I am optimistic,” he said.

The Mexican leader has consistently played down the pandemic, questioning the value of wearing masks and refusing to wear one himself in most public appearances.

On Friday, he posted a photo of himself indoors, again