Strategy to eradicate polio in Nigeria
Context
In the early 2000s, wild poliovirus transmission was interrupted from the majority of Nigeria but continued in the north of the country. This was due to persistent low coverage during routine immunization and supplementary immunization activities, resulting from a weak health system and the effect of rumours about vaccine side-effects.
Polio virus from the northern states repeatedly re-infected polio-free states and neighbouring countries. In response, federal authorities established an emergency task force, culminating in the signing of the 'Abuja Commitments to Polio Eradication' by state Governors in February 2009. In addition, in mid-2009, His Eminence the Sultan of Sokoto established a ‘National Task Team of Northern Traditional Leaders’ to address the situation. Improvements in supplementary immunization activities were made, resulting in a 50% decline in overall cases by end-2009 compared with 2008 and a 90% decline in poliovirus type 1 cases.
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 Nigeria
Interrupting the remaining poliovirus transmission in Nigeria requires the following activities.
(a) Institutionalizing the new tactics that rapidly raised supplementary immunization coverage in the northern states in 2009. The primary focus will be building on the achievements of 2009 by extending the strategies employed at state level to the district level. Particular attention will be given to identifying the highest-risk districts and to ensure that district chairpersons are engaged and accountable for performance of supplementary immunization activities. In these areas, district-specific plans will be developed based on the local context and challenges.
(b) Scaling-up international technical support to intensify eradication activities.
(c) Expanding social mobilization and communications capacity.
(d) Implementing nationwide ‘Immunization Plus Days’ to maintain the high levels of population immunity needed to reduce the risk of outbreaks following importations into the polio-free areas of the country. Bivalent oral polio vaccine is anticipated to be used extensively in these supplementary immunization activities, as a complement to the use of trivalent oral polio vaccine.
(e) Conducting ‘mop-up activities’ as appropriate with monovalent OPVs.
(f) Strengthening surveillance of acute flaccid paralysis.
Eradication targets
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End–2010: <10% 0-dose children (per non-polio acute flaccid paralysis data) in each of the 12 high-risk states (including the eight persistent transmission states).
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End–2011: >80% of children with >3 doses of oral polio vaccine (per non-polio acute flaccid paralysis data) in each of the 12 high-risk states (including the eight persistent transmission states).
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End–2012: >90% of children with >3 doses of oral polio vaccine in all states.