Sexually Transmitted Diseases:
Letters to the Editor
Department of Infectious Disease Epidemiology, Imperial College London, London, UK
New York, NY
To the Editor:
In a recent issue of Sexually Transmitted Diseases, McCreesh and colleagues1 model the potential effect of reducing sexual partnership concurrency over a 10-year period on HIV incidence among a population in rural Uganda. Based on this, the authors conclude that interventions to reduce concurrency would have only a modest impact. Although the modeling answers an important theoretical question about the impact of a hypothetical intervention that reduces concurrency alone, owing to the artificial nature of the modeled intervention, the results should not be used to draw conclusions about the impact of a successful “network-based” behavior change communication intervention.
In the model, when concurrency is reduced, the total number of partnerships and sexual acts in the population is conserved by redistributing concurrent partnerships to individuals with no partners. This standard hypothetical approach is useful for isolating the effect of concurrency in mathematical network models.2 However, it is highly unlikely to reflect the impact of a successful real-world intervention because there is no reason to believe that such compensatory behavior would occur in real life. Why would people with no partners take on new partnerships in response to such a campaign? As the authors themselves note, a successful concurrency intervention would likely affect many sexual behavior indicators simultaneously. In rural Zimbabwe, for example, declines in new HIV infections coincided with reductions in concurrency, casual partnerships, total multiple partnerships, and the proportion of sexually active adolescents.3–5 In Uganda, the Zero Grazing campaign, which addressed all types of multiple partnerships, coincided with steep declines in both casual sex and HIV transmission.6 Although concurrency was not measured, this behavior also probably declined.
Between 2009 and 2010, a number of behavior change communication campaigns using the imagery of “concurrency” and “sexual networks” to encourage partner reduction were supported by the US Agency for International Development in eastern and southern Africa. The model results presented here—although valuable in the theoretical exposition of the relation between network features and HIV transmission—should not be interpreted as an evaluation of those approaches.
Instead, these and other behavior change campaigns should be evaluated using scientific studies with biologically measureable end points. If well designed and executed, such studies could greatly improve our understanding of whether and how sexual behaviors might change in response to this innovative messaging. Limited preliminary evaluations suggest that some of these campaigns have had positive effects on self-reported behaviors and attitudes,7,8 but resources for the programs themselves and their rigorous scientific evaluation are now being scaled back, whereas tremendous resources are being devoted to the evaluation of new biomedical prevention strategies. Only thorough evaluation of all intervention activities will give policy makers the information they need to identify and promote the most effective and efficient prevention programs.
Jeffrey W. Eaton
Timothy B. Hallett
Department of Infectious
Imperial College London,
New York, NY
1. McCreesh N, O’Brien K, Nsubuga RN, et al.. Exploring the potential impact of a reduction in partnership concurrency on HIV incidence in rural Uganda: A modeling study. Sex Transm Dis 2012; 39: 407–413.
2. Morris M, Kretzschmar M. Concurrent partnerships and the spread of HIV. AIDS 1997; 11: 64–68.
3. Gregson S, Garnett GP, Nyamukapa CA, et al.. HIV decline associated with behavior change in Eastern Zimbabwe. Science 2006; 311: 664–666.
4. Gregson S, Gonese E, Hallett TB, et al.. HIV decline in Zimbabwe due to reductions in risky sex? Evidence from a comprehensive epidemiological review. Int J Epidemiol 2010; 39: 1311–1323.
5. Morris M, Epstein H. Response to: Gregson S, Gonese E, Hallett TB, et al. HIV decline in Zimbabwe due to reductions in risky sex? Evidence from a comprehensive epidemiological review. Int J Epidemiol 2011; 40: 836.
6. Kirby D. Changes in sexual behaviour leading to the decline in the prevalence of HIV in Uganda: Confirmation from multiple sources of evidence. Sex Transm Infect 2008; 84: ii35–ii41.
7. Uganda Health Marketing Group. “Get Off the Sexual Network: One Love” Communication Campaign on Multiple Concurrent Partners. Paper presented at: Africomnet Awards Practicum; 2010; Johannesburg, South Africa.