Table XI.

Model Inputs for the Northern Nigeria Model

Model input (symbol)	Best estimate	Source	Notes
Number of subpopulations	2		Subpopulation 1: undervaccinated subgroups (1/10th of total population); subpopulation 2: general population (9/10th of total population)
Relative population size compared to all of Nigeria	0.256	104	Population of the 7 states in the Northwest Zone (i.e., Jigawa, Kaduna, Kano, Katsina, Kebbi, Sokoto, Zamfara) divided by total population of Nigeria, according to the 2006 census
Number of age groups	10		0–2, 3–11 months; 1; 2; 3; 4; 5–9; 10–14; 15–39*; ≥ 40 years*
umber of mixing age groups	3		0–4; 5–14; ≥ 15 years
Year when model run-up starts	1970
Year when R0 seasonality starts	1980
Year when die-out first allowed	1980
Average basic reproductive number (R0) (PV1)	8		Fitted within range for middle tier (Table III); PV2&3 according to ratios in Table I
Proportional change in R0 due to seasonality ($\alpha$)	0.05		Comparatively less seasonality than in temperate climate countries
Day of seasonal peak in R0(pd)	60 (March 1)		Most outbreak peaks occurred early in recent years
Proportion of contacts reserved for individuals within the same mixing age group ($\kappa$)	0.4		For simplicity, assume equal values for each mixing age group
Proportion of potentially infectious contacts of individuals in subpopulation 1 that are with other individuals in subpopulation 1 (pwithin)	0.88	13	Force of infection as a result of mixing between subpopulations modeled using previously described approach(13) (see Appendix A1)
Proportion of transmissions via oropharyngeal route ($p^{oro}$)	0.3	19	Based on approximate average of mean expert assessments for community and close contacts for type 1 in high R0 settings(19)
Per-dose take rate (tr) (PV1;PV2;PV3)
- tOPV	0.45;0.7;0.4
- mOPV	0.66;NA;0.65
- bOPV	0.54;NA;0.52
Routine coverage with 3 or more doses by 1 year of age, birth dose coverage, and partial coverage	Time series 1984–2012	76, 88	See Appendix A4 for values used
Characterization of routine tOPV vaccination, 1984–2012		101
- Doses at birth	1
- Cumulative effect of 3 primary nonbirth doses at ages (months)	3
Characterization of OPV campaigns 1996–2012			See Appendix A4 for detailed assumptions about SIAs in each year and resulting annual cumulative percentages of missed children
- Dates, durations, and target population of SIAs	Time seriesa
- Effective per-round impact ($\zeta$)	Varies
- Target age groups	0–4 years

Acronyms: bOPV = bivalent OPV; mOPV = monovalent OPV; NA = not applicable; OPV = oral poliovirus vaccine; PV1,2,3 = poliovirus type 1, 2, and 3, respectively; SIA = supplemental immunization activity; tOPV = trivalent OPV

^*Age groups marked with an asterisk indicate age groups that count towards determining the fraction of newborns who receive maternal antibodies, based on the immune fraction in those age groups (see Appendix A1).

^aInformation about SIA history as reported to WHO and elsewhere.^{(42,102,103,105–109,117,124)}