Economic evaluation using dynamic transition modeling of ebola virus vaccination in lower-and-middle-income countries

Figures & data

Figure 1. Schematic view of the dynamic transmission model.

Table 1. Model input parameters – baseline values, ranges, and distributions applied for sensitivity analyses.

Variable	Value	Range*	Distribution	Reference
Population size	1,000			Model assumption
Initially infected	1			Model assumption
Transmission rate ($\beta$)/day	0.330		Beta	^14
Incubation rate (ξ)/day	0.190		Beta	^14
Infectious rate (γ)/day	0.180		Beta	^14
Recovery rate (δ)/day	0.030		Beta	Calculated
Case fatality rate (200 days)	0.810		Beta	^14
Case fatality rate/day	0.140		Beta	Calculated
Basic reproductive number (R0)	1.830		Beta	^14
Disability weight for EVD	0.133	0.139–0.298	Beta	^29
Vaccine efficacy	100%	79–100%	Lognormal	^30
Vaccine coverage proportion	50%			Assumed based on herd immunity threshold
Cost of vaccine bundle ($)	33.54		Gamma	^25^,^26
Cost of vaccination kit ($)	17.26		Gamma	^25^,^26
Cost of vaccine storage and management ($)	66.45		Gamma	^25^,^26
Cost of screening ($)	18.49		Gamma	^31
Cost of treating a case of EVD	86.72	83.59–90.07	Gamma	^32
Personal cost for treating EVD case	6.16	5.96–6.37	Gamma	^32
Median age in DRC	19.2		Normal	^16
Life expectancy of DRC	60.97		Normal	^17

*Variables without published ranges were varied by ±10%.

Table 2. Infections, deaths and DALYs averted by vaccination in a population of 1,000.

Outcome	No vaccination	Vaccination	Outcomes averted	Percentage reduction attributable to vaccination
Infections	676	5	671	99.26%
Deaths	543	4	539	99.08%
DALYs	22,209	187	22,022	99.16%

DALY disability adjusted life year.

Figure 2. Graphical representation of dynamic transmission model without (Panel A) and with vaccination (Panel B).

Table 3. Results of base case cost-effectiveness analysis.

	Vaccination	No vaccination
Total cost	$6,804,616.21	$4,723,258.42
Incremental cost	$2,081,357.80
Infections	5	676
Infections averted		671
ICER per infection averted		$3,100.64
Deaths	4	543
Deaths averted		539
ICER per death averted		$3,869.05
DALYs	187.29	22,208.80
DALYs averted		22,022
ICER per DALY averted		$94.51

ICER incremental cost effectiveness ratio; DALY disability adjusted life year. Values in bold are ICERs; representing the cost-effectiveness.

Figure 3. Results of one-way sensitivity analyses. Abbreviations. ICER, incremental cost effectiveness ratio; DALY, disability adjusted life year.

Figure 4. Tornado plot showing compiled one-way sensitivity analyses of model parameters. Middle line represents the base case incremental cost utility ratio (ICER) per disability adjusted life year (DALY) averted ($94.51). Horizonal bars represent the variations in the ICERs as a result of variations in model parameters.

Figure 5. Heat maps showing incremental cost-effectiveness ratio (ICER) per disability-adjusted life year (DALY) averted from varying vaccination coverage and other parameters. Green areas represent favorable ICERs, red areas represent least favorable ICERs.

Figure 6. Incremental cost-effectiveness ratio (ICER) planes for the cost-effectiveness of EVD vaccine. Abbreviation. DALY, disability adjusted life year. Upper panel represents iterations of ICERs per infections and deaths averted. Lower B represents iterations of ICER per DALY averted.

Figure 7. Cost-effectiveness ratio acceptability curve for the cost-effectiveness of EVD vaccine in terms of DALYs averted. Abbreviation. DALY, disability adjusted life year.

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