The Delta Plus variant of COVID-19, which could be an even more contagious mutation of the Delta variant that’s currently infecting people around the world, is beginning to spread to new regions.

Officials in South Korea say they’ve confirmed two cases of Delta Plus, one in a man in his forties with “no recent travel records” and the second from a person who recently returned from the U.S. The second confirmed case had reportedly received both doses of AstraZeneca’s coronavirus vaccine.

Delta Plus, which the World Health Organization lists as a “variant of concern,” was first detected in the U.K. in June. It has since been found in several other countries, including the U.S., India, China, Russia, and Japan.

It’s uncertain at this point how concerned people should be about this variant. Data about the variant is still preliminary, which has led some health officials to wonder if the upgrade from "variant of interest" to one of concern might have been premature.

As of July 23, there were 70 cases of the Delta Plus variant in India, according to the Hindustan Times. At least 39 have been discovered in the U.K.

Delta Plus has not yet shown that its mutations give it a contagion advantage over the Delta variant or other mutations. Infections, so far, have primarily been in younger people. And while the data is still preliminary, it seems that antibodies in vaccinated people are still effective against this variant. Experts warn those findings could shift, though, since the sample size is still very small.

Delta Plus is just one of several variants officials are keeping their eye on as COVID-19 continues to spread.