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J Infect Dis. 2014 Nov 1;210 Suppl 1:S412-23. doi: 10.1093/infdis/jit834.

Modeling strategies to increase population immunity and prevent poliovirus transmission in the high-risk area of northwest Nigeria.

Author information

1
Kid Risk, Inc, Orlando, Florida Delft University of Technology, Delft, The Netherlands.
2
Kid Risk, Inc, Orlando, Florida.

Abstract

BACKGROUND:

Nigeria continues to struggle in its efforts to eliminate circulating live polioviruses using oral poliovirus vaccine (OPV).

METHODS:

We modeled population immunity, and we estimated cases and the timing of transmission die-out for numerous policies that could accelerate the elimination of wild poliovirus type 1 (WPV1) and help Nigeria manage the risks of circulating vaccine-derived polioviruses (cVDPVs). We used a differential-equation based poliovirus transmission and OPV evolution model focused on northwest Nigeria to characterize the impact and trade-offs of potential vaccination strategies, including the introduction of inactivated poliovirus vaccine (IPV).

RESULTS:

Northwest Nigeria appears close to reaching the threshold of population immunity it must exceed to stop WPV1 transmission if it continues immunizing previously under-vaccinated children. Avoiding type 2 cVDPVs (cVDPV2s) will depend on using sufficient amounts of trivalent OPV, which will also reduce the risks of cVDPV2s after coordinated cessation of type 2-containing OPV (OPV2). Using IPV during the OPV cessation period may increase population immunity, but it leads to a much lower impact on cVDPV risks than ensuring sufficient trivalent OPV use prior to OPV2 cessation.

CONCLUSIONS:

Northwest Nigeria needs to intensify and sustain its immunization efforts to achieve and maintain higher levels of population immunity.

KEYWORDS:

IPV; OPV; eradication; polio; population immunity

PMID:
25316863
DOI:
10.1093/infdis/jit834
[Indexed for MEDLINE]

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