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Polio eradication

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The eradication of poliomyelitis (polio) remains a global priority to which all African countries are committed. Since 1988, when the World Health Assembly resolved that polio should be eradicated, significant progress has been made. Today, only four countries globally are known to have indigenous wild poliovirus transmission. An independent evaluation of the major barriers to interrupting wild poliovirus transmission carried out in 2009 concluded that polio eradication is feasible, provided that managerial, security and technical issues can be addressed.

At its Sixty-first Session in May 2008, the World Health Assembly called for a new plan to complete the eradication. Consequently, a special 1-year Global Polio Eradication Initiative programme of work was developed and implemented in 2009. On evaluation of this Initiative, it was concluded that with stronger political and financial commitments, the remaining barriers to achieving eradication could be addressed. Development of a new 3-year Global Polio Eradication Initiative Strategic Plan from 2010 to 2012 has therefore been agreed, with the goal of interrupting wild poliovirus transmission within that period. This plan was approved by the World Health Assembly in May 2010.

Contents

Epidemiology of wild poliovirus

In 2010, a total of 75 wild poliovirus (WPV) cases have been reported in 10 countries, compared with 545 WPV cases in 2009 in 15 countries. This progress is attributable to the marked drop in WPV cases reported from Nigeria, the only African country with indigenous wild poliovirus transmission. Three African countries have re-established polio transmission, namely Angola, Chad and Democratic Republic of the Congo.

Polio eradication in Nigeria has remained problematic, as a large number of children remain unvaccinated in a number of high-risk states and local government areas. This problem is compounded by low routine immunization coverage, gaps in surveillance as evidenced by the presence of orphan viruses, and low political commitment in some areas.

Circulating vaccine-derived polioviruses, largely resulting from low routine immunization coverage, were reported in three countries in 2009, namely Democratic Republic of the Congo, Guinea and Nigeria. Seventeen cases were confirmed in 2010.

A total of 16 annually accredited polio laboratories have been established in African countries as part of the global network.

Polio supplementary immunization activities

In response to circulating WPVs, at least two rounds of polio supplementary immunization activities were implemented in a synchronized manner in 19 countries of west and central Africa. These reached over 86 million children aged under 5 years. Two or more additional rounds and mop-up activities were implemented in priority countries in 2010. Despite commendable efforts to implement high-quality supplementary immunization activities, there have been significant challenges in making available the required quantities of the appropriate vaccine as well as all the necessary funding.

Independent monitoring has been instituted as a way of validating the reported coverage of the polio campaigns. Findings are used to take immediate corrective action, while lessons learned serve to institute corrective measures in subsequent campaigns. Written feedback is provided to each country following analysis of the independent monitoring data. Findings show that the most common reasons for children’s absence during supplementary immunization activities are:

  • limited awareness of caretakers
  • absence of children from home when the vaccinators arrive
  • failure to cover all settlements as a result of inadequate planning.

Surveillance for acute flaccid paralysis

Surveillance for acute flaccid paralysis is fully institutionalized in all 46 countries of the WHO African Region. Acute flaccid paralysis surveillance indicators are monitored and reported weekly. The infrastructure in place for acute flaccid paralysis surveillance also supports surveillance for other vaccine preventable diseases, as well as for other diseases of public health importance. These include measles, yellow fever, and maternal and neonatal tetanus.

Certification of polio eradication

The Africa Regional Certification Commission was established by WHO in 1998. The Commission has successfully constituted national certification committees, national polio expert committees and national task forces to support the polio eradication process.

Twenty-five countries have now been certified polio free by the Africa Regional Certification Commission. However, 11 of these countries experienced importation of wild polioviruses during the 2009 outbreak. Containment measures are taking place.

Remaining challenges

  • Sustaining advocacy at national level and ensuring that commitment at the highest level is translated into action at the operational level.
  • Strengthening health systems to better support routine immunization.
  • Improving the quality of supplementary immunization activities to reduce the number of children missed, especially in hard-to-reach areas.
  • Ensuring availability of the appropriate type of vaccine in the required amounts and in a timely manner.
  • Bridging the financial gap for both surveillance and supplementary immunization activities.