Today marks one year since we have had a case of the wild poliovirus anywhere in Africa, the last having been reported from Somalia with a date of onset of 11th August 2014.

What an extraordinary achievement and what a powerful symbol of the progress that has been made on the African continent over the past generation.

What got us to this point was not just a vaccine, it was the tireless work of hundreds of thousands of volunteers, traditional and religious leaders at community level, combined with the commitment and determination of national and local governments. On the global level it has involved a remarkable partnership between WHO, Rotary International, the Centres for Disease Control, the Bill and Melinda Gates Foundation and UNICEF, backed by the generous contributions of many public and private donors.

Last month we applauded Nigeria for having achieved a year without detection of the wild poliovirus, despite the enormous challenges posed by insecurity in the Northeast of the country. We have also seen polio outbreaks in Cameroon, Equatorial Guinea and the Horn of Africa halted, thanks to the professionalism, ingenuity and courage of UNICEF staff and our partners.

Globally, we are on the verge of totally eradicating a disease for only the second time in history – as we approach the General Assembly’s endorsement of the Sustainable Development Goals, what a wonderful time to be able to encourage the global community to set ambitious goals and to know that such goals can be met – if we believe.

In November I will end a career of nearly forty years in development. On the 15th of August 1977 I set off for Khartoum. In the months and years that followed I travelled extensively throughout Sudan – on the top of trucks, by train, at the wheel of a Land Rover on nearly impossible roads, and by paddle steamer down the Nile. During these journeys I gained an appreciation for the enormous size of the country and for the extraordinary hardship and isolation in which many of its population lived. I left Sudan in 1983, as the civil war was starting and returned in 2007, as Director of the UNICEF programme in the South of what was then still a united country.

In 2008 we had an outbreak of polio that originated in Jonglei State, close to the border with Ethiopia. It is hard to describe the isolation of this place – an area of marshes, vast cotton-soil plains that become impassable after rains, and an area that has long been plagued by insecurity. Despite all of these challenges – and ongoing insecurity and conflict to this day – the polio outbreak was contained and, what is now the independent nation of South Sudan, has not seen a single case of wild poliovirus since.

Similar remarkable achievements across Africa have provided the basis for what we celebrate today.

While today’s milestone is extraordinary, it is not an endpoint. For Nigeria, two more years must pass without a case of wild poliovirus before it can finally be certified as polio-free, along with the rest of the African continent. To achieve this goal, Nigeria and the many other African countries that remain at risk for polio must maintain high-quality surveillance, work ever-harder to improve the quality of vaccination campaigns, and act decisively, should further outbreaks occur. They must also re-double their efforts to improve routine immunization.

With Africa now on track, we are left with only two countries where polio transmission has never been interrupted: Pakistan and Afghanistan. Here too, despite enormous challenges, communities, governments and partners are working with courage and determination to end polio once and for all: today’s anniversary in Africa gives us the faith to believe that they too can succeed.

Peter Crowley is the head of UNICEF’s Polio unit.