(NEXSTAR) — Minnesota health officials confirmed Monday that a mutation of COVID-19 from Brazil was found for the first time in the United Sates.

The case involves a patient who recently returned to Minnesota after traveling in Brazil, according to a news release from the Minnesota Department of Health.

The unidentified Twin Cities resident started feeling ill during the first week of January and underwent testing Jan. 9.

Minnesota health officials said the variant, known as the Brazil P.1, was found thanks to the department’s variant surveillance program. Each week the program collects 50 random samples from local laboratories and for use in their “whole genome sequencing” program, which helps categorize the different variants and gives “a more accurate picture of what specific forms of COVID-19 are circulating in Minnesota.”

There was no immediate indication that the variant was spreading in the state.

Viruses are constantly mutating, and new versions – called variants – often emerge. Health officials are also worried about variants that were first reported in the United Kingdom and South Africa. Researchers believe they may spread more easily than the virus that’s been sickening millions in the United States and that has caused nearly 420,000 deaths.

The Brazilian variant was first identified in four travelers who were tested at an airport outside Tokyo, Japan. It contains a set of mutations that may affect its ability to be recognized by antibodies, according to the U.S. Centers for Disease Control and Prevention.

Some researchers have raised a concern that the Brazilian variant may be able to re-infect people who already were sickened by COVID-19.

More than 217,000 people in Brazil have died of the virus since the pandemic began, according to Johns Hopkins University data. There have been over 8,844,000 confirmed cases.

The Associated Press contributed to this report.