Table 1.
Model parameters for vaccine cost-effectiveness and impact analyses of ETEC and Shigella vaccines. All costs are presented in 2016 US$. *Values for the base case scenarios. **Range of values used in sensitivity analysis. ‘NA’ indicates parameters that were not varied in sensitivity or uncertainty analyses.
| Model input | Values* | Uncertainty distribution | Sensitivity range** | Reference |
|---|---|---|---|---|
| Mortality and morbidity | ||||
| Population estimates | Varies by country and administration unit | NA | NA | [19] |
| Under-5 diarrheal mortality (deaths) | Lognormal (SD) | |||
| DRC | 25,840 | 7655 | ± 10% | [24], [25] |
| Kenya | 5737 | 695 | ± 10% | [24], [25] |
| Zambia | 2797 | 695 | ± 10% | [24], [25] |
| Zimbabwe | 3696 | 680 | ± 10% | [24], [25] |
| Annual change in non-rotavirus under-5 diarrheal mortality rate | Triangular (min, max) | |||
| DRC | −0.017 | −0.021, −0.013 | ± 25% | [24], [25] |
| Kenya | −0.032 | −0.040, −0.024 | ± 25% | [24], [25] |
| Zambia | −0.054 | −0.068, −0.041 | ± 25% | [24], [25] |
| Zimbabwe | 0.052 | 0.039, 0.065 | ± 25% | [24], [25] |
| Under-5 diarrheal episodes per child-year | 3.3 | Lognormal (SD = 0.9) | ± 10% | [26] |
| Annual change in under-5 diarrheal episode rate | ||||
| DRC | −0.012 | NA | NA | [24] |
| Kenya | −0.003 | NA | NA | [24] |
| Zambia | −0.005 | NA | NA | [24] |
| Zimbabwe | 0.005 | NA | NA | [24] |
| Etiological fraction attributed to ETEC for AFRO region | 0.075 | Beta (alpha = 100.7, beta = 1231.1) | ± 25% | [22], [23] |
| Etiological fraction attributed to Shigella for AFRO region | 0.082 | Beta (alpha = 101.5, beta = 1126.3) | ± 25% | [22], [23] |
| Stunting induced by ETEC episodes (shift in HAZ) | 0.068 | Beta (alpha = 156.7, beta = 1231.1) | ± 50% | [4] |
| Stunting induced by Shigella episodes (shift in HAZ) | 0.082 | Beta (alpha = 101.5, beta = 2137.8) | ± 50% | [4] |
| Fraction of diarrheal episodes that are moderate to severe | 0.10 | Beta (alpha = 21.2, beta = 182.8) | 0.02 – 0.15 | [4], [9], [52] |
| Age-adjusted and discounted DALYs per child death | 34 | NA | NA | [53] |
| Watery diarrhea disability weight | 0.067 | NA | NA | [40] |
| Duration of diarrhea (years) | 0.02 | NA | NA | [40] |
| Diarrheal risk index | ||||
| Susceptibility risk factors | ||||
| Oral rehydration treatment | 93% effective | NA | NA | [32] |
| Underweight (weight-for-age) | Relative risk: 1–12.5 | NA | NA | [18] |
| Vitamin A supplement | 30% effective | NA | NA | [33] |
| Exposure risk factors | ||||
| Drinking water access (relative risk) | ||||
| Unimproved | 1.00 | NA | NA | [34] |
| Off-plot improved | 0.89 | NA | NA | [34] |
| On-plot improved | 0.77 | NA | NA | [34] |
| Sanitation access (relative risk) | ||||
| No, unimproved or shared | 1.00 | NA | NA | [34] |
| Improved and unshared | 0.84 | NA | NA | [34] |
| Improved sewered house connection | 0.31 | NA | NA | [34] |
| Vaccination and medical costs | ||||
| ETEC or Shigella vaccine efficacy | 60% | Beta (alpha = 22.6, beta = 15.4) | ± 20% | Assumption |
| Dose price (2016 US$) | $3.33 | Lognormal; SD = 0.91 | $2.00-$7.00 | Assumption |
| Administration cost (2016 US$) | $1.93 | Lognormal; SD = 0.22 | ± 40% | [38] |
| Outpatient cost of ETEC or Shigella illness (2016 US$/episode) | Lognormal (SD) | |||
| DRC | $4.81 | 0.29 | ± 40% | [54], [55], [56], [57], [58], [59], [60], [61], [62], [63], [64], [65], [66], [67], [68], [69] |
| Kenya | $5.31 | 0.86 | ± 40% | [54], [55], [56], [57], [58], [59], [60], [61], [62], [63], [64], [65], [66], [67], [68], [69] |
| Zambia | $5.47 | 0.88 | ± 40% | [54], [55], [56], [57], [58], [59], [60], [61], [62], [63], [64], [65], [66], [67], [68], [69] |
| Zimbabwe | $4.81 | 0.34 | ± 40% | [54], [55], [56], [57], [58], [59], [60], [61], [62], [63], [64], [65], [66], [67], [68], [69] |
| Inpatient cost of ETEC or Shigella illness (2016 US$/episode) | Lognormal (SD) | |||
| DRC | $24.24 | 5.41 | ± 40% | [54], [55], [56], [57], [58], [59], [60], [61], [62], [63], [64], [65], [66], [67], [68], [69] |
| Kenya | $33.42 | 12.07 | ± 40% | [54], [55], [56], [57], [58], [59], [60], [61], [62], [63], [64], [65], [66], [67], [68], [69] |
| Zambia | $34.34 | 12.40 | ± 40% | [54], [55], [56], [57], [58], [59], [60], [61], [62], [63], [64], [65], [66], [67], [68], [69] |
| Zimbabwe | $23.77 | 7.55 | ± 40% | [54], [55], [56], [57], [58], [59], [60], [61], [62], [63], [64], [65], [66], [67], [68], [69] |
| Inpatient visit rate (percentage of outpatient visits) | 12.50% | Beta (alpha = 26.9, beta = 182.2) | ± 50% | [36] |
| Outpatient visit rate (cases taken to healthcare facility) | ||||
| DRC | 39% | NA | NA | [52] |
| Kenya | 58% | NA | NA | [52] |
| Zambia | 66% | NA | NA | [52] |
| Zimbabwe | 39% | NA | NA | [52] |