The independent Africa Regional Certification Commission (ARCC) for Polio Eradication officially declared that the 47 countries in the UN World Health Organization (WHO) African Region are free of the virus, with no cases reported for four years. Of the 47 countries within the WHO’s Africa region, Nigeria eradicated the virus most recently, and now, four years have passed since the country’s most recent wild polio case. Polio once paralyzed some 75,000 children a year across Africa.

But cases of vaccine-derived polio are still sparking outbreaks of the disease in more than a dozen countries. The World Health Organization (WHO) says this is just the second time a virus has been eradicated in Africa, after the elimination of smallpox four decades ago.

“This is a momentous milestone for Africa. Now future generations of African children can live free of wild polio,” said Dr. Matshidiso Moeti, WHO Regional Director for Africa. The achievement is the result of Herculean vaccination and surveillance efforts by the international community and health care workers, often working in some of the most dangerous areas of Africa.

The final push to combat the wild poliovirus focused largely on northern Nigeria, where the Boko Haram Islamic extremist group has carried out insurgencies for more than a decade. Health workers at times carried out vaccinations on the margins of insecurity, putting their lives at risk. “This is one of the greatest achievements in public health history,” said WHO chief Tedros Adhanom Ghebreyesus. Governments and non-profit organisations have been working since 1996 to try eradicate the virus from the African continent with sustained vaccination campaigns. Almost 9 billion polio vaccines have been delivered, Tedros added.

A large part of the eradication effort has been through the Global Polio Eradication Initiative (GPEI), which was created in 1988 and is led by national governments and five partners, Rotary International, WHO, UNICEF, US Centres for Disease Control and Prevention and the Bill and Melinda Gates Foundation. The GPEI calls on countries and donors to remain vigilant against all forms of polio. Until every strain is eradicated worldwide, the incredible progress made against polio globally will be at risk. The WHO African Region’s success against wild polio has shown the world that progress against some of the biggest global health challenges is possible.