Strategy to eradicate polio in Angola
Context
Conflict in Angola has contributed to a weak health system, low routine immunization coverage and insufficient capacity to fully implement international polio outbreak response guidelines.
These factors have led to circulation of imported wild poliovirus that has persisted for more than 12 months, and the country is classified as having re-established transmission. Poliovirus transmission is highly concentrated in the Luanda-Benguela corridor along the Atlantic coast. Furthermore, in 2009, re-established polioviruses in Angola re-infected other, previously polio-free countries and areas.
The priority in Angola is to enhance the quality of supplementary immunization activities to interrupt the remaining chains of transmission.
Strategic approach in Africa
Compared with Asia, poliovirus transmission persists over a broad area in Africa. In addition, polio outbreaks due to importations generally result in more polio cases over longer periods of time than in Asia. Both are due to weak health systems, resulting in low immunization coverage.
These challenges are off-set by consistently high per-dose efficacy of oral polio vaccine in Africa, and a lower population immunity threshold (80–85%) needed to stop poliovirus transmission.
Consequently, the immunity thresholds needed to stop polio transmission in Africa can be achieved with relatively fewer vaccination campaigns over wide areas and maintaining high coverage.
Strategic approach in Angola
Interrupting the remaining poliovirus transmission in Angola requires the following activities.
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Implementing high-quality mop-up campaigns in the Luanda-Benguela corridor using type 1 monovalent oral polio vaccine.
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Implementing nationwide supplementary immunization activities with bivalent oral polio vaccine and trivalent oral polio vaccine to maintain population immunity in the polio-free areas.
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Enhancing acute flaccid paralysis surveillance to ensure the rapid detection and mop-up of any residual transmission.
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Enhancing resources – particularly international technical assistance and communications – to levels which are comparable to the investment in endemic areas.
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Revising and updating operational guidelines for the quality of supplementary immunization activities. Any districts achieving <90% coverage during any supplementary immunization activity (as verified by independent monitoring) will be re-covered.
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Scaling-up the pilot in late-2009, increasing involvement of military forces, political leaders and district medical doctors in the key re-established transmission areas.
Eradication targets
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End–2010: all re-established wild poliovirus transmission interrupted and <10% missed children in all districts of Luanda, Benguela and Kwanza Sul during each supplementary immunization activity
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End–2011: supplementary immunization activity and acute flaccid paralysis surveillance performance of 2010 sustained.
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End–2012: supplementary immunization activity and acute flaccid paralysis surveillance performance of 2010 sustained.