Strategy to eradicate polio in Chad
Context
Transmission of polio is geographically focal. Operational issues are the main reason children are still being missed by vaccination campaigns, although social and communication problems are also important, particularly in key high-risk areas. Nomadic communities are also at a relatively higher risk of being missed than other groups.
In 2011 Chad was affected by two epidemics: a WPV1 outbreak, which started in N’Djamena in September 2010, and a WPV3 outbreak in the eastern district of Am Dam, which started in November 2007 and re-established transmission. Both were caused by importations from Nigeria. Although the second epidemic is considered to be under control (with no cases detected since March 2011), sub-optimal surveillance warrants caution.
Communication in Action: overview of community engagement.
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 Chad
The publication of the most recent National Emergency Action Plan for Chad covers the period July to December 2012, aims to stop transmission of wild poliovirus by the end of December 2012, and recommends the following emergency approach.
- Four priority areas of action identified: Lake Region; Logone Oriental, Logone Occidental, and Mandoul Tandjilé; Regions Ouaddai, Wadi-Fira, Dar Sila, Salamat and Moyen Chari; N’Djamena and Chari-Baguirmi.
- Carry out immunisation campaigns with Sub-National Immunization Days (SNIDs), using bivalent oral polio vaccine (bOPV).
- Reduce the time to report cases of acute flaccid paralysis (AFP) and specimen collection and increase the number of follow up investigations.
- Identify and use community volunteers in the High-Risk Areas for AFP surveillance.
- Increase awareness of and commitment to polio eradication campaigns among members of the national government, governors and religious leaders.
- Increase participation in routine immunization activities among community-based associations/local NGOs and traditional and religious leaders.
- Establish an accountability system for each level of the health system for the Expanded Programme on Immunisation (EPI) and polio activities and create better coordination between various sub-committees and levels of the programme.
Eradication targets
- Reduce to less than 5% the proportion of children not vaccinated and checked by Independent Monitoring data.
- Ensure that all regions have sufficient OPV stock for Supplementary Immunization Activities (SIAs).
- Achieve 80% AFP rate for all regions.
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