Table 1. Parameters and assumptions harmonized across models.
| Harmonized parameters and assumptions | |
|---|---|
| Demographics | Assumed a roughly constant population size with the age composition of a low-income country (see S1 Text) [20] |
| Crude birth rate: 22.8 births per 1,000 persons per year [20] | |
| Average life expectancy: 64 years (Africa) and 75 years (Asia) [20] | |
| Incidence* | Medium incidence: annual incidence of 52 cases per 100,000 person-years, peak incidence in the 10–15-year age category |
| High incidence: annual incidence of 214 cases per 100,000 person-years, peak incidence in the 2- to 4-year age category | |
| Very high incidence: annual incidence of 1,255 cases per 100,000 person-years, peak incidence in the 2- to 4-year age category | |
| Vaccine delivery strategies | No vaccination |
| Routine vaccination at 9 months with a catch-up campaign 9 months to 15 years | |
| Routine vaccination at 2 years with a catch-up campaign 2–15 years | |
| Routine vaccination at 5 years with a catch-up campaign 5–15 years | |
| Routine vaccination at 9 months + a booster at 5 years with a catch-up campaign 9 months to 15 years; booster doses only administered to previously vaccinated individuals | |
| Vaccine coverage | 9 months: Based on MCV1† coverage estimates for low- and lower-middle-income countries |
| 2 years: Uniform(0.5, 1) × MCV2† coverage estimates | |
| 5 years: Uniform(0.5, 1) × school attendance estimates | |
| Catch-up campaign: Based on Supplementary Immunization Activity estimates | |
| Vaccine effectiveness (against blood-culture-confirmed typhoid fever)$ | Slow-waning: Based on trial data from Malawi [11,13] |
| Age at vaccination <5 years: | |
| 74.4% (1.75 years follow-up), 70.6% (4.61 years follow-up) | |
| Age at vaccination 5–15 years: | |
| 83.7% (1.75 years follow-up), 79.3% (4.61 years follow-up) | |
| Fast-waning: Based on trial data from Bangladesh [12,14] | |
| Age at vaccination <2 years: | |
| 81% (1–2 years follow-up), 24% (3–5 years follow-up), −5% (5–7 years follow-up) | |
| Age at vaccination 2–4 years: | |
| 80% (1–2 years follow-up), 59% (3–5 years follow-up), 14% (5–7 years follow-up) | |
| Age at vaccination 5–15 years: | |
| 88% (1–2 years follow-up), 74% (3–5 years follow-up), 32% (5–7 years follow-up) | |
| Case fatality risk | Africa: 0.81% (95% CI [0.10%, 6.22%]) [3] # |
| Asia: 0.16% (95% CI [0.07%, 0.40%]) [3] # | |
| Treatment probabilities | Region-specific; see Table C.1 in S6 Text |
| Cost of treatment | Age-, treatment-, and region-specific; see Table C.1 in S6 Text |
| Pediatric: ≤15 years old | |
| Adult: >15 years old | |
| Cost of TCV** vaccination | Procurement cost: $1.50, without Gavi support [21] |
| Syringes and safety equipment: average of $0.29 [22] | |
| Delivery cost: strategy- and region-specific; see Table C.1 in S6 Text | |
*See S2 Text for age-specific incidence.
†MCV1, measles containing vaccine first dose; MCV2, measles containing vaccine second dose.
$Vaccine effectiveness estimates used for model fitting. See Table A.1 in S3 Text for model-specific parameter estimates.
#Based on a sub-analysis of studies published since 2010. CI, confidence interval.
**TCV, Typhoid conjugate vaccine.