Strategy to eradicate polio in India
Context
Most of India is polio-free. Persistent transmission of poliovirus is localized in areas of western Uttar Pradesh and central Bihar. Key to the strategy in India is to ensure both areas interrupt transmission simultaneously by addressing the different challenges in each reservoir.
In central Bihar the primary issues relate to achieving high immunization rates among populations in hard-to-reach areas (e.g. the Kosi river basin). In western Uttar Pradesh the population is readily accessible but extremely high levels of population immunity – both humoural and mucosal – are needed to stop poliovirus transmission.
Compounding the problem of achieving high population immunity is the compromised efficacy of oral polio vaccine in these areas. In 2009, however, new clinical trial data demonstrated that very high population immunity (>95%) could be achieved with very high immunization coverage using monovalent oral polio vaccine.
Strategic approach in Asia
In Asia, persistent poliovirus transmission is highly localized in a few districts. The approach in Asia therefore focuses on district- and sub-district-specific plans to achieve exceptionally high coverage with very frequent supplementary immunization activities to boost population immunity to >95% – the threshold required to stop transmission in Asia.
Engaging local political and administrative leaders to ensure the quality of supplementary immunization activities is also important.
Strategic approach in India
To interrupt the remaining poliovirus transmission in India, the Union and State Governments of India have developed a ‘107 high-risk block plan’.
107 high-risk block plan
The ‘107 high-risk block plan’ aims to sustain high-quality supplementary immunization activities through:
- regular review and updating of microplans
- quarterly trainings of staff
- extensive social mobilization and communications
- tracking newborns to facilitate follow-up for routine immunizations
- refining strategies to identify and reach mobile and migrant populations.
In central Bihar, the block plans will focus on refining and implementing the special Kosi river strategy that was developed in 2008–2009 to vaccinate hard-to-reach groups.
In western Uttar Pradesh, the emphasis on supplementary immunization quality will be complemented with a specific research agenda to study strategies for enhancing mucosal immunity and determine the risk factors for polio in highly vaccinated children.
These targeted activities will be complemented by continued national and large-scale subnational immunization days to maintain population immunity in the rest of the country, particularly in those areas at highest risk of importations.
Eradication targets
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End–2010: >95% population immunity to type 1polio in the persistent transmission areas of western Uttar Pradesh and central Bihar.
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End–2011: >95% population immunity to type 1 and type 3 polio in the persistent transmission areas of western Uttar Pradesh and central Bihar.
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End–2012: >95% population immunity to type 1 and type 3 polio maintained.