Effectiveness of a No-Sex or Safe-Sex Month in Reducing HIV transmission/Efficacite D'un Mois D'abstinence Ou De Rapports Sexuels Proteges Pour Reduire la Transmission Du VIH/La Eficacia De Un Mes De Abstinencia O De Sexo Sin Riesgos Para Reducir la Transmision del VIH

Article excerpt


Despite significant investment in programmes for the treatment and prevention of human immunodeficiency virus (HIV) infection, the prevalence of such infection in sub-Saharan Africa remains stubbornly high. In 2009, for example, an estimated 24.8% of the adults living in Botswana and 17.8% of those living in South Africa were thought to be HIV-positive. (1) Prevention is, in general, particularly poor: for every two individuals starting treatment, five become infected with HIV. (2) Recently, many international organizations, including the Joint United Nations Programme on HIV/AIDS (UNAIDS), The World Bank and the World Health Organization (WHO), have called for a realignment of prevention strategies and new, innovative ways to blunt the impact of the HIV epidemic, especially in those countries that are most affected. (3,4) A novel strategy proposed by Parkhurst and Whiteside (5)--a population-wide "month off" from risky behaviour, with no sex or exclusively safe sex over that period--gained a substantial amount of publicity, with articles (6-8) and mentions (9-14) in many high-profile outlets. Unlike most other interventions seeking to modify sexual behaviour, this strategy expects participants to change their behaviour for a relatively short time, albeit once a year. It may also have relatively low set-up and promotional costs. Furthermore, such a "month-off" intervention has the potential for creating a strong national movement (5) and at least two countries, Kenya and Swaziland, are already considering campaigns based on this intervention. (6,15)

As Parkhurst and Whiteside state in their discussion, the crux of the intervention they propose lies in forcing many individuals who are newly infected with HIV to pass through the acute stage of their infection without engaging in any behaviour that may be risky in terms of the transmission of the HIV. (5) The acute phase of HIV infection, which lasts roughly 2 months, is associated with high rates of infectivity. (5) Infectivity drops dramatically following the acute stage and then remains low for several years, until the development of acquired immunodeficiency syndrome (AIDS). (16) A month-long break in risky behaviour could substantially reduce the viral load in a population, not only by interrupting all transmission for a month but also by cutting the number of individuals who are in the acute stage of HIV infection when the risky behaviour resumes. It has been suggested that the prevalences of HIV infection in countries with large Muslim populations are kept relatively low by the Muslim practice of abstaining from sex during the daylight hours of the month of Ramadan. (5)

Since a clinical trial of an annual, month-long break from risky behaviour would be unethical and pose huge logistical problems, Parkhurst and Whiteside suggested that such an intervention should be mathematically modelled, to guide future policy discussions. (5) We therefore constructed a model to assess the impact of a month-long interruption in HIV transmission (the "test intervention") on the prevalence and incidence of HIV infection in three countries in sub-Saharan Africa: Kenya, South Africa and Swaziland. While South Africa was modelled simply as an example of a country where HIV infection is hyperendemic, Kenya and Swaziland were investigated because their governments are considering implementing the test intervention. The model was used to evaluate the potential benefits of the test intervention and to give insight into the associated policy debate. (6,15)


Model structure

Our model replicates the characteristics of the HIV epidemics in Kenya, South Africa and Swaziland. Each of these countries represents a hyperendemic setting for which the relevant data on HIV prevalence and demographics are readily available. The model focuses on the progression of HIV-1 infection among adults aged 15-49 years. The relevant demographic information was provided by the United Nations Population Division. …