A person in California has become the first in the U.S. to have an identified case of the omicron variant of COVID-19.

Dr. Anthony Fauci said the person was a traveler who returned from South Africa on Nov. 22 and tested positive on Nov. 29.

The news comes as scientists continue to study the risks posed by the new strain of the virus.

The Biden administration moved late last month to restrict travel from Southern Africa where the variant was first identified and had been widespread.

Clusters of cases have also been identified in about two dozen other nations.

Answers to 25 common COVID-19 vaccine questions

Vaccinations for COVID-19 began being administered in the U.S. on Dec. 14, 2020. The quick rollout came a little more than a year after the virus was first identified in November 2019. The impressive speed with which vaccines were developed has also left a lot of people with a lot of questions. The questions range from the practical—how will I get vaccinated?—to the scientific—how do these vaccines even work?

Keep reading to discover answers to 25 common COVID-19 vaccine questions.