Table VII.

Model Inputs for the Tajikistan Outbreak Model

Model input (symbol)	Best estimate	Source	Notes
Number of subpopulations	1		Includes 3 regions (of 6 total in the country) in which more than 1 case occurred (i.e., Dushanbe, Khatlon, Districts of Republican Subordination)
Relative population size compared to all of Tajikistan	0.67	85	According to 2007 Living Standards Measurement Survey
Number of age groups	11		0–2; 3–11 months; 1; 2; 3; 4; 5; 6–9; 10–14; 15–39*; ≥ 40* years
Number of mixing age groups	3		0–4; 5–14; ≥ 15 years
Year when model run-up starts	1930
Year when R0 seasonality starts	1935
Year when die-out first allowed	1960
Average basic reproductive number (R0) (PV1)	8		Fitted within range for middle tier (Table III)
Proportional change in R0 due to seasonality (α)	0.5		Assume substantial seasonality in mountainous, continental country
Day of seasonal peak in R(pd)	60 (March 1)		Month of maximum precipitation in Dushanbe (capital)
Proportion of contacts reserved for individuals within the same mixing age group ($\kappa$)	0.3		For simplicity, assume equal values for each mixing age group
Proportion of transmissions via oropharyngeal route ($p^{oro}$)	0.75	19	Fitted within range of expert assessments(19)
Characterization of regular WPV importations			Assume no WPV importations established widespread transmission between the last SIAs in the early 2000s and the outbreak in 2010
- Frequency	Annual
- Day of introductions	91 (April 1)
- First year without introductions	1995
Per-dose take rate (tr) (PV1)
- tOPV	0.4a
- mOPV1	0.65
Routine coverage with 3 or more polio vaccine doses by age 1 year, partial coverage, and birth dose coverage	Time series 1960–2010	76, 85	Coverage based on arbitrary assumption (of 90%) during Soviet era, then based on available surveys
Characterization of routine tOPV vaccination 1960–2010		84–86	Assume birth dose not captured in survey results (i.e., model birth dose as a separate, additional dose), but booster dose (at 12 months) counted towards primary coverage by age 12 months (e.g., a child with a dose at birth and 2, 4, and 12 months gets counted towards coverage with 3 primary polio doses)
- Doses at birth	1
- Cumulative effect of 3 primary nonbirth doses at ages (months)	3
- Relative coverage compared to most recent survey	0.9
Characterization of tOPV SIAs 1995–2002			See Appendix A4 for effective per-round impact assumptions by year in the absence of good data
- Dates, durations, and target population of SIAs	Time seriesb
- Effective per-round impact ($\zeta$)	Varies
Date of introduction for 2010 outbreak	November 1, 2009		Based on model calibration within plausible range
Characterization of outbreak response		3	Assume very high effective per-round impact given high coverage of response campaigns; ignore impact of mop-up rounds in some districts in September (after last case)
- Per-dose take rate (PV1)	0.4
- First day (in 2010), by round (round 1; 2; 3; 4; 5; 6)	May 4; May 18; June 1; June 15; October 4; November 8
- Target ages, by round (rounds 1–2; 3–6)	0–5; 0–14 years
- Vaccine, by round (rounds 1–4; 5–6)	mOPV1, tOPV
- Effective impact ($\zeta$) of each round	0.8
- Duration of each round (days)	5

Acronyms: IPV = inactivated poliovirus vaccine; mOPV1 = monovalent oral poliovirus vaccine type 1; PV1 = poliovirus type 1; SIA = supplemental immunization activity; tOPV = trivalent oral poliovirus vaccine

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

^aFor runs to verify behavior of other serotypes, we use take rates for tOPV of 0.65 and 0.35 for type 2 and 3, respectively.

^bInformation about SIA history as reported to the World Health Organization.