title: Expected epidemiological impact of the introduction of a partially effective HIV vaccine among men who have sex with men in Australia.
abstract: A trial of the ALVAC-AIDSVAX HIV vaccine was recently found to be partially effective in preventing HIV transmission among study participants in Thailand. The success of this trial means that vaccination may become a viable intervention for the prevention of HIV infection in the medium-term future. Assuming that the vaccine has similar relative protective effectiveness per exposure event for reducing transmission among men who have sex with men (MSM) in high-income settings we investigated the potential population-level impact of rolling out such a vaccine among MSM in New South Wales, Australia. Using a detailed individual-based transmission model that simulates a population of sexually active MSM it was found that one-off intervention of 60% or 30% coverage of a vaccine with characteristics like the ALVAX-AIDSVAX vaccine would likely reduce the cumulative incidence of HIV by 9.6% and 5.1%, respectively, over a 10-year period. Due to the waning of vaccine efficacy, a booster vaccination could be required to maintain this reduction in incidence over the long term. If the previously vaccinated population is given a booster vaccine, with the same protection conferred as with the initial vaccination, every 5 years or every 2 years then the cumulative incidence over 10 years for 60% coverage could be reduced by 14.4% and 22.8%, respectively. Such a weak vaccine, with boosting, may be a potential intervention strategy for the prevention of HIV infection in MSM in high-income countries if further trials show boosting to be safe, acceptable, and cost-effective. However, the moderately low population-level impact suggests that a public health strategy involving such a vaccine should be supplemented with other biomedical and educational strategies.
authors.affiliation: National Centre in HIV Epidemiology and Clinical Research, Faculty of Medicine, The University of New South Wales, Sydney, NSW, Australia. rgray@kirby.unsw.edu.au
authors.forename: Richard T
authors.initials: RT
authors.lastname: Gray
authors.forename: Mohammad H
authors.initials: MH
authors.lastname: Ghaus
authors.forename: Alexander
authors.initials: A
authors.lastname: Hoare
authors.forename: David P
authors.initials: DP
authors.lastname: Wilson
mesh_terms: D016915:AIDS Vaccines / Q000008:administration & dosage* / Q000276:immunology; D002944:Circumcision, Male; D006678:HIV / Q000276:immunology / Q000472:pathogenicity; D015658:HIV Infections / Q000453:epidemiology* / Q000276:immunology / Q000517:prevention & control / Q000635:transmission; D006801:Humans; D017589:Immunization Programs / Q000706:statistics & numerical data*; D007117:Immunization, Secondary; D015994:Incidence; D008297:Male; D008962:Models, Theoretical; D009517:New South Wales / Q000453:epidemiology; D016032:Randomized Controlled Trials as Topic; D012725:Sexual Behavior; D012747:Sexual Partners; D014611:Vaccination
chemical_list: D016915:AIDS Vaccines