During a “mop up” search for unvaccinated children, this infant in Angola was first missed and then found and immunized. Continued vigilance is required to prevent polio from re-emerging in countries certified polio-free while eradication is pursued in the dwindling number of endemic countries.

Future Challenges

The final years of polio eradication have been compared to the last leg of a marathon and the final ascent to Everest’s summit. Political and financial commitment must remain high. Complacency, lack of vigilance, and reduced vaccination coverage can threaten countries with reintroduction of the virus from other countries. Relaxed surveillance will jeopardize “poliofree” certification. Developing sound post-eradication policies aimed at safely stopping vaccination and reducing the threat of inadvertent or deliberate reintroduction of virus are high priorities for the global program. Perhaps the most important challenge is to learn how to use the lessons learned from polio eradication to improve all immunization and disease control activities in developing countries.

Keeping Up With Growing Populations
Until global certification is achieved and it is deemed safe to stop polio immunization, supplying countries with sufficient oral polio vaccine so they can continue to immunize their under-5 populations will remain a challenge. The introduction of monovalent P1 Oral Polio Vaccine into some countries with no remaining P2 or P3 virus may tip the scales in favor of interrupting transmission where the virus is particularly challenging to eradicate.