Pete McGinn's COVID-19 diagnosis surprised him because his symptoms were mild. He was even more surprised to find out his infection was caused by a new variant: omicron.

"When I first heard it, I thought it was a supervillain," said McGinn, of Minneapolis, who tested positive for the virus after a recent trip to New York City for an anime convention. "It seems like a villain name to me and so I guess that kind of matches this since it's a virus."

The 30-year-old product analyst for UnitedHealth Group found out right before Thanksgiving that he had been infected with COVID-19. He said he was was asymptomatic, fully vaccinated and received a booster the first week of November.

McGinn's infection was one of the first cases involving the omicron variant to be identified in the United States, and he's spoken out about it over the weekend — to the New York Times and other national media, because he didn't like "the stigma of COVID" and wanted to encourage others to take vaccinations seriously.

"I'm very pro-science, pro-vaccine," he said. "I do believe that the booster and getting the vaccine helps reduce the symptoms that I had. And I would definitely recommend anybody who, when they can, get the booster."

Omicron was first reported Nov. 24 in South Africa, where it spread quickly. The variant prompted another wave of pandemic uncertainty — and some travel bans — around the globe as researchers scrambled to find out more about it.

On Sunday, Dr. Anthony Fauci told CNN's "State of the Union" that omicron appears less dangerous than the dominant delta variant, which is driving hospitalizations across the country. But he urged caution "before we make any determinations that it is less severe or it really doesn't cause any severe illness, comparable to delta," he said.

Health officials continue to say vaccination and boosters help protect against delta and other variants like omicron.

The Minnesota Department of Health announced Dec. 2 that its lab found omicron "from a Minnesota resident with recent travel history to New York City." The state's variant surveillance program made it so Minnesota was among the first states to discover the variant, now confirmed in a dozen states. California reported it first on Wednesday and Minnesota became the second confirmed state on Thursday.

After the health department released the info, McGinn said, he saw people were blaming the convention, Anime NYC 2021, and sharing anti-vaccine remarks.

"A lot of it was just like, 'See, vaccines don't work.' But in my opinion, they absolutely work because they reduce the amount of people who are in the hospital," he said, noting many people in the hospitals are unvaccinated. "You might still get COVID, but it reduces the symptoms based off my experience."

McGinn said 15 of the 30 people he socialized with during the convention — which drew as many as 50,000 people — also tested positive for COVID-19. All of his friends were fully vaccinated, he said.

Health officials haven't determined which variant they all had, he said, and he doesn't know exactly when he was infected. He believes it happened while outside the convention because most attendees were masked.

McGinn flew into New York City on Nov. 18 and returned Nov. 22. Before that, he had flown to Texas for a work trip on Nov. 10 and came back home to Minneapolis three or four days later, he said.

He had planned to spend Thanksgiving at his mother's home in the northern suburb of Champlin, but McGinn heard on Nov. 23 that one of his anime convention friends tested positive for COVID-19, with an asymptomatic case.

McGinn already had a rapid test at home and took it immediately. It came back positive. A test at the Minneapolis Convention Center later that night also came back positive, so he began to quarantine.

"That threw me for a loop because I really wasn't feeling sick," he said.

McGinn said he had a slight runny nose, a little cough that he thought was his asthma and he was exhausted — but he figured that was from four days in New York City walking 15 miles a day around the convention and city with friends, dining and singing karaoke.

The Health Department called him for some routine contact tracing Nov. 29 or 30. But on Dec. 1, he said, he got another call from health officials saying he had the omicron variant.

They asked for names of the people he was with and where they lived, so those states' agencies could test for variants.

McGinn attributes his quick recovery and mild illness to his vaccination and booster. He said he was never concerned because he took the steps to protect himself and others.

"I honestly felt fine the entire time," he said. "I'm more interested in seeing the results, like if more people get this and their reaction to it."

Staff writer Jeremy Olson and the Associated Press contributed to this story.