The World Health Organization (WHO) has added another COVID strain to its list of coronavirus variants to keep an eye on: the COVID-19 Lambda variant.

This particular variant has now spread to more than two dozen countries, with a heavy concentration in South America. Originally identified in Peru last year, the Lambda variant is responsible for 82% of new COVID cases in Peru over the past two months. About a third of cases in Chile over the same time frame were also caused by the Lambda strain, and the U.K. is among the countries that have seen a smattering of cases. In mid-June, it was first deemed a variant of interest by the WHO—a designation given to a variant which may be more transmissible than the original strain, has caused outbreaks in multiple countries, or theoretically could cause more severe COVID illness or be more adept at evading currently available treatments and vaccines.

At this point, as is the case with other variants such as the Delta variant, it’s too early to know whether the Lambda could be more deadly than other strains or whether it’s resistant to vaccines or treatments.

An increase in transmissibility doesn’t necessarily mean that a variant is more deadly. Take the case of Pfizer/BioNTech’s COVID vaccine, which may only be about 64% effective in preventing the Delta variant’s spread or minor COVID symptoms but is still more than 90% effective in preventing serious illness or hospitalization, according to new research out of Israel.