The World Health Organization and US health officials stated on Friday that they are actively monitoring a new variation of Covid-19, BA.2.86, but the potential impact is still unknown.

The WHO designated the new variation as one under surveillance “due to the large number (more than 30) of spike gene mutations it carries,” according to a pandemic advisory issued late Thursday.

The variation has only been found in Israel, Denmark, and the United States so far.

In a message on the social network X, formerly known as Twitter, the US Centers for Disease Control stated it is also closely watching the strain.

According to the WHO, there are only four known sequences of the variation.

“The potential impact of the BA.2.86 mutations is currently unknown and is being carefully evaluated,” the WHO added.