| Parameter |
Description |
Baseline value (range) |
Ref. |
| |
Epidemic parameters (pre-intervention)1:
|
|
|
| βm |
Male HIV acquisition risk per act |
0.0038
(0.0021 - 0.0068) |
[33] |
| βw |
Female HIV acquisition risk per act |
0.003
(0.0019 - 0.0046) |
[33] |
| βr |
Relative transmissibility of drug-resistant HIV |
0.75 (0.5-1) |
[20] |
| 1/μ |
Average time to remain sexually active |
35 years (30-40) |
[34, 44] |
| dr,d |
Annual rate of progression to AIDS for individuals infected with resistant and wild-type HIV |
1/10 (1/12-1/7) |
[45, 46] |
| nw,nm |
Average number of sexual acts per year for women and men |
70 (60 – 100) |
[31, 32] |
| ρw,Ρm |
Average number of sexual partners per year for women and men |
1.5 (1-2) |
[31, 32] |
| c |
Rate of condom use in general population |
30% (20%-40%) |
[31, 32] |
| αc |
Condom efficacy per act |
90% (80-95%) |
[47] |
| P |
HIV-prevalence in absence of PrEP |
21% (1-35%) |
[1] |
| R0 |
Basic reproduction number in absence of PrEP |
1.27 (1.01- 1.55) |
calculated |
| |
• Intervention parameters2:
|
|
|
| k |
Fraction of PrEP users among new recruits |
60% (40%- 80%) |
assumed |
| k1 |
Initial fraction of the population who decide to use PrEP |
k (40%- 80%) |
assumed |
| σ |
Fraction of PrEP users with prescription who share their pills with untracted users |
10% (0%-20%) |
assumed |
| γa |
Relative PrEP efficacy for sharers |
50% (0%- 100%) |
assumed, [20] |
| γr |
Relative PrEP efficacy for users exposed to drug-resistant HIV |
25% (0%- 100%) |
assumed, [20] |
| αs |
PrEP efficacy in reducing susceptibility per act |
70% (50%- 90%) |
assumed,
[5-7] |
| αi |
PrEP efficacy in reducing infectiousness per act |
70% (50%- 90%) |
assumed |
| re |
Rate of condom replacement in PrEP users |
10% (0%- 20%) |
assumed |
| r |
Annual rate to develop resistance if acquire HIV when using PrEP (perfect adherers) |
2 (1- 4) |
assumed, [20] |
| r1 |
Annual rate to develop resistance if acquire HIV when using PrEP (sharers) |
γar(0-4) |
assumed |
| θ |
Reduction in the initial fraction of HIV positive individuals who start using PrEP (pre-introduction control) |
80% (60- 100%) |
assumed |
| 1/δ |
Duration of continuous usage of PrEP after HIV acquisition (prescribed users) |
6m (4m-1y) |
assumed, [20] |
| 1/δ1M. |
Duration of continuous usage of PrEP after HIV acquisition (secondary sharers) |
5y (2y-10y) |
assumed |
| τ |
Annual rate of resistance reversion for infected former PrEP users who developed drug resistance when on PrEP |
3 (2- 4) |
assumed, [20] |
| τ1 |
Annual rate of resistance reversion for individuals infected with drug-resistant HIV acquired through transmission |
0.25 (0.1- 0.5) |
assumed, [20] |
1Ranges for epidemic parameters are sampled uniformly to obtain parameter sets which are filtered to select 1000 epidemics with R0>1 and HIV prevalence between 1%
and 35% in absence of PrEP.
2Ranges for intervention parameters are used in multivariate sensitivity analysis.