Abstract O1-S07.01 Table 1

Main assumptions and results summary

Main parameters assumptionsRanges of values in the 20 best fits*
Probability of HIV transmission per VI during asymptomatic phase woman to man / man to woman0.0013–0.0019/0.0013–0.0019
Duration / increase in infectivity (RRPI) (relative to asymptomatic phase) in each HIV stagesPrimary/high =6 months/9.2-fold
Asymptomatic/low =8 years/onefold
Late/medium =1 year/7.3-fold
Number of sex acts per partner per year30
Average number of partners per year2
Overall fraction using condoms during AI or VI (Condom efficacy)50% (0.90)
a = Degree of mixing between AI and non-AI (a= 0 AI with AI and exclusively VI with exclusively VI, a= 1: proportionate mixing)0.16–0.71
RRRAI = % Increase in HIV risk per RAI (compared to VI)7.9 to 19.5-fold
RRIAI = % Increase in HIV risk per insertive AI (compared to VI)Twofold
Fraction of the population who practice AI11.5%–13.3%
Fraction of the population who do not practice AI (non-AI or exclusive VI)86.7–88.5%
Fraction of all sex acts of AI group which are AI women / men25.3%–52.7%/21.8%–51.8%
Overall fraction of all sex acts which are AI (%AI)2.9–6.7%
Annual rate of AI who stop AI and become exclusively VI (numbers who leave AI = no who enter AI from VI, in proportion to their respective HIV prevalence)0.068–0.352
Results
HIV prevalence simulated:
 Among AI / among non AI (exclusively VI)19.0%–24.8%/6.8%–11.5%
 Overall population8.5%–12.9%
Cumulative fraction of HIV infections (PAF) annually in mature epidemic due to:
Anal intercourse
 Women/men24.7%–54.4% / 9.4%–22.4%
 Overall population17.3–40.0%
Primary phase of HIV infection (ie, recent infections)
 Women/men23.7%–26.8%/27.3%–37.0%
 Overall population25.5%–31.2%
Ratio of PAF due to AI: PI
 Women/men1.04–2.14/0.34–0.61
 Overall population0.67–1.30
  • * Out of 1000 combinations explored.