Use a condom throughout sex every time, and never share needles
Using a condom throughout sex every time reduces heterosexual HIV transmission by more than 70%. “Most of the time” offers much less protection, little different from not using one in the source's account. Condoms also protect against infections such as syphilis and gonorrhea.
What it takes
A condom costs roughly RMB 1–2 in China. Consistency, including putting it on before sex begins, is the main challenge.
What you may gain
A meta-analysis of 25 studies covered 10,676 heterosexual couples in which one partner had HIV and the other did not—known as serodiscordant couples. Consistent condom use reduced transmission by about 71% compared with never using condoms (RR 0.29, 95% CI 0.20–0.43), and by about 77% compared with inconsistent use (RR 0.23, 95% CI 0.13–0.40). The authors concluded that condoms are imperfect but consistent use reduces HIV transmission by over 70%. They also offer protection against other sexually transmitted infections, including syphilis, gonorrhea and chlamydia.
Context & considerations
Consistent use throughout every encounter is essential; irregular use and no use differ little in the source's account. Sharing needles is a separate efficient transmission route, including drug injection, tattooing and piercing. People at high risk can also use pre-exposure prophylaxis (PrEP), medication taken before exposure. Across 18 studies, trials with adherence above 70% found approximately 70% lower HIV risk than placebo: risk ratio 0.30, 95% CI 0.21–0.45. Low-adherence trials showed no protective effect. PrEP requires a prescription; consult an infectious-disease clinic or CDC rather than purchasing it online yourself. For action after an exposure, see Chapter 13.
Research & references
Giannou FK, Tsiara CG, Nikolopoulos GK, et al. (2016). Condom effectiveness in reducing heterosexual HIV transmission: a systematic review and meta-analysis of studies on HIV serodiscordant couples. Expert Review of Pharmacoeconomics & Outcomes Research, 16(4), 489-499. https://doi.org/10.1586/14737167.2016.1102635 ; Fonner VA et al. (2016). Effectiveness and safety of oral HIV preexposure prophylaxis for all populations. AIDS. https://doi.org/10.1097/QAD.0000000000001145 (PrEP).