Percent increase in HIV prevalence forecasted by 11 ‘best fit’ parameter value sets, under scenarios depicted in figure 2 (% increase compared to scenario of no ART or no behaviour change)
| Modelled parameter value set | |||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Scenario | Year | 1 | 2 | 3* | 4 | 5 | 6 | 7 | 8 | 9 | 10* | 11* | Mean (SD) |
| Probability of transmission on ART=0.5% female to male. No ART enrolment in HIV stages 1 or 2 (figure 2A) | |||||||||||||
| Rate of ART init starting stage 3 | |||||||||||||
| 0.25/year | 2015 | 1.3 | 11.2 | 0.4 | −0.4 | 7.4 | 6.0 | 13.0 | 10.2 | 10.6 | 9.3 | 12.7 | 7.4 (4.9) |
| 2025 | 6.5 | 19.3 | 5.5 | 4.5 | 14.3 | 14.2 | 20.7 | 19.4 | 18.4 | 16.9 | 21.4 | 14.6 (6.3) | |
| 1.00/year | 2015 | 1.8 | 23.4 | −0.2 | −3.7 | 14.4 | 11.5 | 28.6 | 21.8 | 23.2 | 20.2 | 27.9 | 15.4 (11.5) |
| 2025 | 9.9 | 39.0 | 7.9 | 1.6 | 26.8 | 27.2 | 43.7 | 39.5 | 38.2 | 33.9 | 45.0 | 28.4 (15.4) | |
| Probability of transmission on ART=2.0% female to male. No ART enrolment in HIV stages 1 or 2 (figure 2B) | |||||||||||||
| Rate of ART init starting stage 3 | |||||||||||||
| 0.25/year | 2015 | 6.6 | 14.8 | 4.9 | 2.5 | 15.5 | 14.8 | 17.8 | 17.6 | 16.2 | 16.8 | 15.0 | 13.0 (5.5) |
| 2025 | 16.7 | 24.1 | 13.9 | 10.4 | 25.8 | 27.1 | 27.0 | 31.5 | 26.2 | 31.2 | 24.7 | 23.5 (6.9) | |
| 1.00/year | 2015 | 14.2 | 32.6 | 10.6 | 3.3 | 34.7 | 32.8 | 39.7 | 39.1 | 36.1 | 36.8 | 33.6 | 28.5 (12.7) |
| 2025 | 32.9 | 50.9 | 27.5 | 15.5 | 55.5 | 57.1 | 58.8 | 66.2 | 56.4 | 64.8 | 53.2 | 49.0 (16.3) | |
| Probability of transmission on ART=0.5% female to male. ART enrolment begins in HIV stage 1 (figure 2C) | |||||||||||||
| Rate of ART init | |||||||||||||
| 0.25/year | 2015 | −10.7 | 21.9 | −10.7 | −19.0 | 13.4 | 14.0 | 21.1 | 15.6 | 21.8 | 2.7 | 23.3 | 8.5 (15.4) |
| 2025 | −4.1 | 44.7 | −4.3 | −21.5 | 30.1 | 37.5 | 42.3 | 39.4 | 44.2 | 14.4 | 49.2 | 24.7 (24.5) | |
| 1.00/year | 2015 | −30.9 | 17.1 | −25.2 | −33.6 | 6.7 | 10.9 | 17.2 | 7.7 | 24.5 | −3.9 | 18.8 | 0.8 (21.2) |
| 2025 | −41.1 | 35.5 | −25.5 | −46.8 | 12.0 | 27.4 | 32.2 | 21.6 | 47.5 | 1.2 | 43.7 | 9.8 (33.6) | |
| Probability of transmission on ART=2.0% fem ale to male. ART enrolment begins in HIV stage 1 (figure 2D) | |||||||||||||
| Rate of ART init | |||||||||||||
| 0.25/year | 2015 | 16.0 | 44.2 | 12.2 | −4.5 | 61.0 | 58.8 | 50.4 | 56.0 | 53.3 | 36.0 | 39.7 | 38.4 (21.6) |
| 2025 | 42.7 | 72.8 | 36.5 | 6.2 | 98.5 | 102.0 | 81.2 | 98.7 | 87.9 | 74.1 | 71.0 | 70.1 (30.1) | |
| 1.00/year | 2015 | 17.2 | 69.9 | 14.7 | −12.9 | 102.2 | 96.6 | 80.0 | 89.3 | 85.7 | 52.2 | 61.3 | 59.7 (37.9) |
| 2025 | 41.2 | 105.0 | 41.1 | −10.6 | 151.5 | 153.9 | 119.2 | 143.1 | 129.8 | 95.5 | 100.4 | 97.3 (52.7) | |
| Probability of transmission on ART=0.5% female to male. ART enrolment begins in stage 2 at rate 0.9/year (figure 2E) | |||||||||||||
| Change partner turnover rate | |||||||||||||
| Increase by 12.5% | 2015 | 10.3 | 6.4 | 7.1 | 9.6 | 10.9 | 8.8 | 7.5 | 8.5 | 6.2 | 6.6 | 6.0 | 8.0 (1.7) |
| 2025 | 14.5 | 6.3 | 10.0 | 16.2 | 14.7 | 10.4 | 8.0 | 9.9 | 6.5 | 9.2 | 5.5 | 10.1 (3.6) | |
| Increase by 50% | 2015 | 43.2 | 19.9 | 32.9 | 65.6 | 40.9 | 34.4 | 25.0 | 31.0 | 24.0 | 30.9 | 20.6 | 33.5 (13.1) |
| 2025 | 58.7 | 19.2 | 45.7 | 110.0 | 48.0 | 36.1 | 25.4 | 33.9 | 24.1 | 43.2 | 18.6 | 42.1 (25.9) | |
| Probability of transmission on ART=2.0% female to male. ART enrolment begins in stage 2 at rate 0.9/year (figure 2F) | |||||||||||||
| Change partner turnover rate | |||||||||||||
| Increase by 12.5% | 2015 | 9.8 | 3.1 | 8.0 | 12.0 | 6.1 | 6.0 | 3.7 | 5.2 | 5.0 | 8.4 | 3.5 | 6.4 (2.8) |
| 2025 | 12.0 | 2.9 | 9.5 | 18.7 | 6.0 | 6.2 | 3.9 | 5.1 | 4.9 | 10.5 | 3.6 | 7.6 (4.7) | |
| Increase by 50% | 2015 | 41.6 | 11.6 | 35.1 | 71.1 | 24.8 | 24.8 | 14.4 | 20.6 | 20.7 | 38.7 | 12.9 | 28.8 (17.4) |
| 2025 | 47.8 | 10.8 | 39.2 | 101.2 | 23.4 | 25.1 | 15.3 | 20.2 | 19.4 | 47.8 | 13.1 | 33.0 (26.1) | |
*Though parameter value sets 3, 10, and 11 provided good model fits to empirically estimated prevalence, we believe they are less likely than the others because they estimated the HIV epidemic peaking too early (see figure 3).
ART, antiretroviral therapy.