Table 2.
Analysis of robustness of the estimates of the incidence of chronic HCV after the introduction of a vaccination program to several alternate parameter values. We examined three targeting strategies, A. no targeting, B. risk targeting, and C. sero-targeting and a high vaccination rate (1% of the population per month).
| Incidence of chronic HCV (ppy) (SD) | ||||||||
|---|---|---|---|---|---|---|---|---|
| No vaccine | 50% efficacy | 80% efficacy | ||||||
| Domain | Assumption/parameter | Parameter estimates or assumptions | Prior to vaccine program initiation | 10 years after vaccine program introduction | 30 years after vaccine program introduction | 10 years after vaccine program introduction | 30 years after vaccine program introduction | |
| Base case | See Table 1. | 13.6 (1.8) | A. B. C. |
10.7 (1.9) 8.0 (1.5) 6.2 (1.2) |
5.3 (1.1) 5.3 (1.1) 5.1 (1.1) |
9.1 (1.5) 4.8 (0.85) 3.2 (0.87) |
2.6 (0.65) 2.4 (0.59) 2.3 (0.65) |
|
| Acute versus chronic infectivity | βA,RNS: βC,RNS Ratio of acute versus chronic infectivity (base case is 0.073:0.0073 [10:1]) | 0.0098:0.0098 (1:1) | 12.6 (1.4) | A. B. C. |
9.8 (1.2) 7.5 (1.1) 6.0 (1.0) |
5.2 (0.90) 4.8 (0.70) 4..8 (0.81) |
8.5 (1.2) 5.3 (0.95) 3.3 (0.66) |
2.5 (0.55) 2.3 (0.52) 2.3 (0.53) |
| AES infectivity (per-event) | βC,AES (base case is 0.0023) | 0.0006 | 6.3 (1.1) | A. B. C. |
4.6 (0.93) 3.3 (0.86) 3.2 (0.82) |
2.7 (0.75) 2.5 (0.76) 2.5 (0.73) |
3.9 (0.94) 2.0 (0.59) 1.7 (0.52) |
1.2 (0.45) 1.1 (0.39) 1.0 (0.41) |
| 0 | 2.9 (0.78) | A. B. C. |
2.1 (0.61) 1.4 (0.46) 1.8 (0.51) |
1.3 (0.45) 1.2 (0.42) 1.2 (0.42) |
1.7 (0.58) 0.75 (0.33) 1.2 (0.41) |
0.62 (0.29) 0.47 (0.25) 0.50 (0.27) |
||
| RNS infectivity (per-event) | βC,RNS (base case is 0.0073) | 0.02 | 14.7 (2.0) | A. B. C. |
11.8 (1.6) 9.0 (1.4) 6.8 (1.2) |
6.0 (1.1) 5.8 (1.0) 5.8 (1.0) |
10.3 (1.6) 6.0 (1.2) 3.8 (0.76) |
3.2 (0.74) 2.9 (0.58) 2.9 (0.71) |
| Vaccine series completion of those initiating | (Base case: 25%, 50%, and 25% receive 1, 2, and 3 doses respectively) | 100% receive 3 vaccinations | 14.0 (2.1)* | A. B. C. |
9.9 (1.7) 6.4 (1.2) 4.6 (1.0) |
3.9 (0.91) 3.6 (0.81) 3.6 (0.84) |
8.0 (1.4) 3.4 (0.78) 1.5 (0.50) |
0.96 (0.37) 0.92 (0.37) 0.86 (0.42) |
| Behavior change at the start of Phase 2 | % enter population in low-, medium-, and high-risk groups (base case is 40, 20, 40) | 0, 0, 100 | 21.9 (2.5) | A. B. C. |
19.3 (2.4) 19.8 (2.4) 9.6 (1.6) |
8.6 (1.6) 9.0 (1.5) 7.9 (1.3) |
17.2 (2.2) 17.9 (2.1) 5.2 (1.2) |
4.7 (0.88) 4.2 (0.82) 3.9 (0.88) |
| 60, 20, 20 | 11.4 (1.8) | A. B. C. |
8.0 (1.4) 6.2 (1.3) 4.8 (0.99) |
4.0 (0.82) 4.0 (0.86) 3.8 (0.79) |
6.3 (1.1) 3.8 (0.89) 2.4 (0.59) |
1.9 (0.55) 1.7 (0.47) 1.6 (0.54) |
||
| HCV re-infection | cPI Probability of entering partially protected susceptible state after spontaneous clearance of initial acute infection (base case cPI=0.50) | 0.0 (Everyone who clears becomes fully susceptible to re-infection) | 19.5 (2.5) | A. B. C. |
15.0 (2.2) 10.6 (1.7) 7.7 (1.2) |
6.5 (1.3) 6.4 (1.2) 6.1 (1.1) |
12.1 (1.8) 6.6 (1.3) 4.2 (0.96) |
3.1 (0.60) 2.8 (0.67) 2.8 (0.70) |
| 1.0 (Everyone who clears becomes partially immune to re-infection) | 10.6 (1.7) | A. B. C. |
8.6 (1.3) 6.1 (1.1) 4.8 (0.93) |
4.2 (0.96) 4.0 (0.91) 4.3 (0.77) |
7.0 (1.3) 4.0 (0.91) 2.8 (0.73) |
2.1 (0.65) 2.0 (0.61) 2.0 (0.60) |
||
*
Differs from base case due only to stochastic fluctuation