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The Spectrum projection package: improvements in estimating incidence by age and sex, mother-to-child transmission, HIV progression in children and double orphans
  1. J Stover1,
  2. P Johnson2,
  3. T Hallett3,
  4. M Marston4,
  5. R Becquet5,6,
  6. I M Timaeus7
  1. 1Futures Institute, Glastonbury, Connecticut, USA
  2. 2US Census Bureau, Washington, DC, USA
  3. 3Department of Disease Epidemiology, Imperial College London, London, UK
  4. 4Department of Population Studies, London School of Hygiene and Tropical Medicine, London, UK
  5. 5INSERM, unité 897, Centre de recherche ‘Epidémiologie et Biostatistique,’ Bordeaux, France
  6. 6Institut de Santé Publique Epidémiologie Développement (ISPED), Université Victor Segalen Bordeaux 2, Bordeaux, France
  7. 7Department of Population Studies, London School of Hygiene and Tropical Medicine, London, UK
  1. Correspondence to Mr John Stover, Futures Institute, 41A New London Turnpike, Glastonbury, CT 06033, USA; jstover{at}


Background The Spectrum program is used to estimate key HIV indicators from the trends in incidence and prevalence estimated by the Estimation and Projection Package or the Workbook. These indicators include the number of people living with HIV, new infections, AIDS deaths, AIDS orphans, the number of adults and children needing treatment, the need for prevention of mother-to-child transmission and the impact of antiretroviral treatment on survival. The UNAIDS Reference Group on Estimates, Models and Projections regularly reviews new data and information needs, and recommends updates to the methodology and assumptions used in Spectrum.

Methods The latest update to Spectrum was used in the 2009 round of global estimates. This update contains new procedures for estimating: the age and sex distribution of adult incidence, new child infections occurring around delivery or through breastfeeding, the survival of children by timing of infection and the number of double orphans.

  • HIV
  • modelling
  • AIDS
  • estimates
  • epidemiology

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  • Funding The AIM module in the Spectrum software and manuals and training materials were developed with funding from USAID (Geneva) and UNAIDS (Washington, DC).

  • Competing interests None.

  • Provenance and peer review Not commissioned; externally peer reviewed.