A crippling strain of polio virus is no more. Officials confirmed Thursday that global health efforts have wiped it out, moving humanity one step closer to completely eradicating the highly infectious virus from the planet.

The obliterated strain—wild poliovirus type 3 (WPV3)—is one of only three wild strains of polio. It is the second to be globally eradicated. Health officials declared WPV2 eradicated in 2015. That leaves only one wild strain remaining: WPV1.

This “historic” announcement falls on World Polio Day and is based on the recent conclusion of the independent Global Commission for the Certification of Poliomyelitis Eradication, set up in part by the World Health Organization. The announcement comes after years of careful and painstaking global surveillance to certify that WPV3 no longer exists anywhere in the world, apart from specimens preserved in secure containment. The last known case of WPV3 occurred in northern Nigeria in 2012.