South Korea has detected its first two cases of the “Delta plus” variant of COVID-19, the country said Tuesday. The Delta plus variant, not to be confused with its horrible Delta predecessor, is said to latch onto lung cells more easily, be more resistant to therapies, and is supposed to be overall more transmissible than previous COVID-19 variants. The announcement comes as many parts of the world rethink reopenings due to the initial Delta variant.

The “plus” variation on the Delta name comes from a mutation in a spike protein, though it’s not one that has caused considerable differentiation from the original Delta variant, per The Washington Post. Other countries to log cases of Delta plus include the U.S., the United Kingdom, and India, though the U.K. has found the current COVID-19 vaccines to still be effective. Meanwhile, Japanese researchers have found South America’s Lambda variant to be more resistant to vaccines, noting its protein mutations make it even more infectious.