Polio: from eradication to systematic, sustained control
The Global Polio Eradication Initiative was established in 1988 when polio was endemic in 125 countries causing some 350 000 clinical cases per year. Today, the number of polio cases has been reduced by 99.9% and polio remains endemic in only three countries—Pakistan, Afghanistan and possibly Nigeria.
This is a great success of the global community. However, after a number of missed deadlines and investments of US$20 billion, the eradication goal has still not been achieved. The challenges of the ‘last mile’ of eradication seem insurmountable. They comprise political instability and community resistance on one hand.
On the other hand, secondary epidemics abide, initially due to wild-type polio virus imported from endemic countries and now due to circulating vaccine-derived polio viruses. The latter epidemics originate from back-mutations of oral polio vaccine (OPV) viruses regaining neurovirulence under conditions of low immunisation coverage and weak health systems.
Finally, the challenges of the global transition from OPV to inactivated polio vaccine, of destroying all OPV stocks, of controlling polio spread from long-term excreters, and of preventing deliberate spread of de-novo synthesised polioviruses have to be overcome. Under all likely scenarios, polio vaccination will need to be continued for decades, or indefinitely.
We argue that the global community should celebrate the massive reduction in polio cases, and then shift course from polio eradication to a more realistic goal of sustained, systematic control, along with increased investments into routine vaccine delivery systems within the frame of Universal Health Coverage.