A highly aggressive and contagious variant of the human immunodeficiency virus (HIV) has been silently spreading in the Netherlands for decades, and researchers have finally identified it.

Like the coronavirus, the virus that causes AIDS (acquired immunodeficiency syndrome) has mutated into a slew of variants — some more dangerous than others. The newfound variant, called VB, appears to progress about twice as quickly as closely related strains.

Individuals infected with the VB variant are likely to develop AIDS within two to three years after diagnosis if they don’t receive treatment, rather than the typical six- to seven-year progression, researchers wrote in the journal Science.