Preventing sexual transmission

The epidemiology of HIV within the UK indicates that the greatest risk of infection is still associated with particular behaviours or demographic characteristics. Identified behaviours with the highest risk of HIV infection are: sex between men, injecting drug use; sex with injecting drug users, and sexual contact in parts of Africa and other parts of the world, where heterosexual transmission predominates.

While there has been massive expenditure on HIV prevention over the last decade, until recently there has been a dearth of high-quality evaluation and little evidence from randomised trials to demonstrate effectiveness of different interventions. However, there is now a growing evidence base to support targeted HIV prevention interventions, tailored to the cultural context and needs of particular groups. A small number of randomised trials have shown the interventions to be effective in reducing the frequency of specific risk practices (for example, unprotected penetrative vaginal or anal intercourse) and, in a few cases, the incidence of new STI. In general, these interventions have aimed to provide basic HIV/AIDS education (including instruction on correct and appropriate condom use), enhance motivation for behavioural change, and teach risk reduction and safer sex negotiation skills (including the ability to resist pressure for sex) and have been delivered in community, small group and individual settings.

Box 16.2 Practises that reduce the risk for acquisition or transmission of HIV

• Using condoms for all penetrative sexual intercourse

• Using adequate quantities of water-based lubricant for both vaginal and anal intercourse.

• Reducing numbers of sexual partners

• Adopting sexual practises that carry a lower risk for HIV transmission (for example, oral sex, mutual masturbation)

• Avoiding recreational drug use during sexual activity, or when sex is likely to happen

• Ensure timely screening and treatment for suspected STI

• For young people, delaying the age at which first sexual intercourse takes place

However, effective interventions in a research setting may not yield the same results in “real life”. Careful consideration of local HIV epidemiology with a critical view of the generalisability of the intervention, will help to determine whether a specific intervention is appropriate and prevent spending limited resources on a programme that shows little benefit, or worse still, a negative effect. The literature contains examples of both.

No single intervention strategy is likely to be sufficient to address all of a group's prevention needs. There is no evidence that “single-shot” prevention interventions have enduring effectiveness at a population level. Interventions need to be sustained, with careful monitoring to indicate when changes are necessary, and must adapt, particularly, to the evolving epidemiological, social and cultural changes in successive new generations.

Little has changed with respect to the core content of prevention messages: it requires sexual contact involving the exchange of body fluids or blood-to-blood contact for transmission to occur. Those who know they are HIV negative and in a mutually monogamous relationship, are not at risk of infection through sex. To limit sexual risk of infection, the most effective strategies are to reduce numbers of sexual partners, know about partners' previous sexual and drug-use history and adopt safer sex practices (for example, oral sex, mutual masturbation and use condoms). Although condoms do not provide total protection, correct and consistent use will substantially reduce the sexual risk of HIV, STI and pregnancy.

The challenge that remains is how to deliver innovative HIV prevention messages through a range of different community, and individual focused interventions to reduce HIV transmission.

The following sections examine some effective strategies in relation to specific populations at high risk.