Related Experiment Video
Updated: Mar 29, 2026

Pairwise Growth Competition Assay for Determining the Replication Fitness of Human Immunodeficiency Viruses
Published on: May 4, 2015
A Method to Estimate the Size and Characteristics of HIV-positive Populations Using an Individual-based Stochastic
Fumiyo Nakagawa1, Ard van Sighem, Rodolphe Thiebaut
1From the aResearch Department of Infection and Population Health, UCL, London, United Kingdom; bStichting HIV Monitoring, Amsterdam, The Netherlands; cINSERM, Centre INSERM U897, Bordeaux, France; dDepartment of Infectious Disease Epidemiology, Imperial College London, London, United Kingdom; eDepartment of Microbiology, Tumor and Cell Biology, Karolinska Institute, Stockholm, Sweden; fDepartment of Clinical Microbiology, Karolinska University Hospital, Stockholm, Sweden; gEuropean Centre for Disease Prevention and Control (ECDC), Stockholm, Sweden; hCEEISCAT, Generalitat de Catalunya, Barcelona, Spain; iWHO Regional Office for Europe, Copenhagen, Denmark; jInstitute of Clinical Trials and Methodology, UCL, London, United Kingdom; kDivision of Infectious Diseases and Hospital Epidemiology, University Hospital Zurich, Zurich, Switzerland; lResearch Department of Primary Care and Population Health, UCL, London, United Kingdom; mCHIP @ Department of Infectious Diseases, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark; nDepartment of Hygiene, Epidemiology and Medical Statistics, University of Athens Medical School, Athens, Greece; oUCL Institute of Child Health, UCL, London, United Kingdom; and pPublic Health England, London, United Kingdom.
Abstract:
It is important not only to collect epidemiologic data on HIV but to also fully utilize such information to understand the epidemic over time and to help inform and monitor the impact of policies and interventions. We describe and apply a novel method to estimate the size and characteristics of HIV-positive populations. The method was applied to data on men who have sex with men living in the UK and to a pseudo dataset to assess performance for different data availability. The individual-based simulation model was calibrated using an approximate Bayesian computation-based approach. In 2013, 48,310 (90% plausibility range: 39,900-45,560) men who have sex with men were estimated to be living with HIV in the UK, of whom 10,400 (6,160-17,350) were undiagnosed. There were an estimated 3,210 (1,730-5,350) infections per year on average between 2010 and 2013. Sixty-two percent of the total HIV-positive population are thought to have viral load <500 copies/ml. In the pseudo-epidemic example, HIV estimates have narrower plausibility ranges and are closer to the true number, the greater the data availability to calibrate the model. We demonstrate that our method can be applied to settings with less data, however plausibility ranges for estimates will be wider to reflect greater uncertainty of the data used to fit the model.
Related Concept Videos
Statistical Methods for Analyzing Epidemiological Data
Analysis of Population Pharmacokinetic Data
Estimating Population Standard Deviation
Steps in Outbreak Investigation
Mechanistic Models: Compartment Models in Individual and Population Analysis

