Use a condom for the whole of every sexual act, and don't share needles with anyone
- High value
- Evidence A
- Buys life
- Costs a little
- Takes minutes
- Some willpower
In plain words
Worn every time and throughout, a condom cuts the chance of passing on HIV between a man and a woman by roughly 70% or more. Using one “most of the time” does little better than not using one. It also blocks syphilis, gonorrhea and the like.
- Cost
-
One or two CNY each. The hard part isn't the money; it is using one every time, from the very start.
- What you get
-
One study pooled 25 studies and 10676 heterosexual couples. In each couple one partner had HIV and the other did not, which is technically called serodiscordant. Compared with people who never used one, people who used condoms consistently every time had about a 71% lower risk of passing on HIV (RR 0.29; 95% CI 0.20 to 0.43, the plausible range). Compared with people who used them on and off, it was about 77% lower (RR 0.23, 95% CI 0.13 to 0.40). The authors concluded that although condoms are imperfect, “consistent use can reduce HIV transmission by more than 70%.” The same protection also covers other sexually transmitted infections such as syphilis, gonorrhea and chlamydia.
- Notes
-
The gap between “irregular use” and “no use” is small; it works only if you use one every time and throughout. Sharing needles is a separate, highly efficient route of transmission unrelated to sex, and it includes injecting drugs, tattooing and piercing. People at high risk can also use pre-exposure prophylaxis (PrEP), which means taking medicine beforehand to block infection. Pooling 18 studies, in the trials where more than 70% of people took their pills on schedule, people taking PrEP had about a 70% lower risk of HIV infection than those taking placebo (risk ratio 0.30; 95% CI 0.21 to 0.45, the plausible range). In the trials where few people took them on schedule, no protection was seen. PrEP is a prescription drug; ask at an infectious disease clinic or the local CDC, and don't buy it online yourself. For what to do after an exposure has already happened, see §13.
- Evidence grade
- A : Specific numbers from meta-analyses, large cohorts or randomized trials; for law and policy, the statute or official text.
- Sources
-
- 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 等 (2016). Effectiveness and safety of oral HIV preexposure prophylaxis for all populations. AIDS. https://doi.org/10.1097/QAD.0000000000001145（暴露前预防 PrEP）
Mentioned in
- If you are a man who has sex with men and has high-risk sex, ask a designated HIV hospital about pre-exposure prophylaxis; taken on schedule, it cuts infections by more than 70%
- Don't pay for sex: the default penalty is detention of 10 to 15 days, not just a fine
- If you may have been exposed to HIV, get the preventive medicine within 72 hours, the sooner the better
Translated from the Chinese original. Original book, section 1, tip 30. This section is about health and medicines. It is general information, not a substitute for a doctor’s diagnosis or prescription. Content may be out of date and rules differ by place. When you actually deal with an agency, a doctor or a court, follow what local officials, doctors and lawyers tell you. Disclaimer