Mexican officials confirmed Friday that the first case of the omicron variant of the coronavirus has been detected in the country.

The first known case of the Omicron variant in Mexico was detected in a 51-year-old patient who returned from a trip to South Africa in late November.

Officials say the person has only mild symptoms and is being treated in a Mexico City hospital.

"It's already in Canada. In the United States. In other places. That's why it's called a pandemic," said President Andrés Manuel López Obrador, noting that Mexican officials had expected the omicron variant to show up in the country.

Health officials urged people to remain calm and continue following proven prevention measures, including mask-wearing, social distancing and getting vaccinated. But leaders said they do not consider closing borders a useful tool in containing the virus.