Respondent-driven sampling: empirical evaluation and methodological development

Lead Research Organisation: London Sch of Hygiene and Trop Medicine
Department Name: Epidemiology and Population Health

Abstract

A new method of gathering data on vulnerable groups in society has been proposed, called Respondent Driven Sampling.

Research is needed to assess how well Respondent Driven Sampling works in collecting high-quality data, and also to explore if the method could be improved.

This research will test whether Respondent Driven Sampling works in London university students and fishermen in Uganda. It will also evaluate and extend the theory on which Respondent Driven Sampling is based using state-of-the-art statistical inference and computational modelling

If Respondent Driven Sampling can be shown to work well, it will allow researchers and public heath workers to monitor trends in highly-vulnerable groups such as sex-workers and injecting drug users. Data that could be used, for example, to see whether HIV prevention programs in these groups are succeeding or failing.

Technical Summary

Background
Respondent Driven Sampling(RDS) has recently been proposed as a method of collecting unbiased representative data on Hidden or hard-to-reach population subgroups that are often key to the maintenance of infectious diseases in human populations. RDS estimation theory is based on a non-standard, indirect, procedure that first makes inferences about the sample population‘s social network and then makes inferences about the target population.

This non-standard approach has hindered the methodological development and validation of RDS and, to date, only one study has attempted to evaluate RDS by comparing data collected using RDS with representative contemporaneous data from the same population. This study, an internet-based RDS survey of Cornell university students, failed to estimate the proportion male within the method‘s 95% plausible range, reinforcing earlier concerns that RDS may not generate representative data, even in easily-accessible populations. Despite this, RDS has quickly become popular, over 123 RDS studies have been published and RDS is also being employed to provide data for public health decision making by major funding bodies (Centers for Disease Control and Prevention and Family Health International).

RDS has the potential to address important epidemiological issues, but the theoretical basis of RDS is poorly understood and the key statistical questions remain unanswered. There is an urgent need to empirically validate RDS and develop appropriate statistical methods to analyse data collected using RDS.

Aim
The aim of this Fellowship is to evaluate whether RDS can generate representative population-based samples and to further develop the methodology required to analyze data collected in RDS studies.

Objectives
1. To validate face-to-face RDS among fishermen in rural Uganda using representative population-based data as the gold standard
Design: Compare a cross-sectional RDS sample of 600 fishermen in rural Uganda wiepresentative population based data.
2. To validate internet-based RDS among London graduate students using whole-population institutional data as the gold standard, and to explore the impact of temporal filtering.
Design: Two cross-sectional web-based RDS surveys, each collecting data on 500 students in the same London University.
3. To evaluate and extend the theory on which RDS is based using the results of (1) and (2) and state-of-the-art statistical inference and computational modelling by:
a. Assessing the performance of the existing RDS point and interval estimators and seek to identify alternative estimators that offer improved performance.
Design: Methodological development and statistical modelling using STATA, WinBUGS, R and Matlab.
b. Use simulation network modelling to assess the characteristics of at-risk populations and RDS survey strategies for which RDS is most able to generate representative data.
Design: Network simulation modelling using C++.
4. To produce practical recommendations for researchers to conduct RDS studies in a ‘Toolkit‘; Outputs: Toolkit and documentation on custom functions in standard statistics analyis packages
5. To initiate further studies to validate RDS using representative data on hidden populations. Proposed design: Comparison of data from cross sectional face-to-face RDS studies with representative samples on the same hidden population

Publications

10 25 50

publication icon
Chapman R (2010) Do behavioural differences help to explain variations in HIV prevalence in adolescents in sub-Saharan Africa? in Tropical medicine & international health : TM & IH

 
Description Course - Introduction to impact and economics of TB control
Geographic Reach Multiple continents/international 
Policy Influence Type Influenced training of practitioners or researchers
Impact Trained medical professionals in quantitative methods to use in their decision making at country and global level.
 
Description Evidence used to set WHO post-2015 Global TB Targets
Geographic Reach Multiple continents/international 
Policy Influence Type Citation in other policy documents
Impact My group generated evidence that was used to set ambitious WHO post 2015 global TB targets. This should have major impact on TB financing and control policies and practice over the next 15 years.
 
Description Global Fund Distribution of Funding by Disease
Geographic Reach Multiple continents/international 
Policy Influence Type Participation in advisory committee
Impact I directly contributed to debate and the (eventual) consensus that led to an increase in proportion of funds allocated by the Global Fund to Tuberculosis. Global reach. Should increase survival and morbidity by reducing TB disease (no quantitative evidence yet)
 
Description Led creation of 'STROBE-RDS': Reporting Guidelines for Respondent Driven Sampling Surveys
Geographic Reach Multiple continents/international 
Policy Influence Type Membership of a guideline committee
Impact Peer reviewed reporting guidelines have been published, have been incorporated into submission guidelines for at least two academic journals (2016), have already been cited in papers reporting findings from RDS surveys. This will increase the value of data collected using RDS. This should lead to improved health and funding decisions targeted (primarily) at the control and prevention of HIV, and later, improved survival, morbidity and quality of life, and the efficiency of health care delivery.
URL http://www.ncbi.nlm.nih.gov/pubmed/26112433
 
Description Organised Symposium on RDS at International STI meeting to help STI practioners and researchers understand the current limitations of data collected using RDS
Geographic Reach Multiple continents/international 
Policy Influence Type Influenced training of practitioners or researchers
Impact Much verbal feedback during and afterwards that symposium greatly helped practioners and researchers better understand the current limitations of RDS. Editorial written based on this symposium with the aim of influencing policy regarding the interpretation of data collected using RDS. It also included the first guidelines for the reporting of RDS studies (STROBE-RDS).
 
Description Published Introductory Infectious Disease Modelling book for training clinicians, epidemiologists and public health professionals
Geographic Reach Multiple continents/international 
Policy Influence Type Influenced training of practitioners or researchers
Impact The book has sold well (~2000 copies by mid 2013) and widely (Africa, Australia, Eurasia, North and South America) since its release in May 2010. The book is accompanied by extensive exercises and training materials that have been downloaded over 500 times by mid 2013(http://anintroductiontoinfectiousdiseasemodelling.com/). Material from the book have been directly incorporated into at numerous university courses, including the Harvard and Princeton. This will have directly affected the ability of these students and public health professionals to interpret and use mathematical modelling in their work.
URL http://anintroductiontoinfectiousdiseasemodelling.com/
 
Description Set up Infectious Disease Modelling Course in Distance Learning format for training health professionals (particularly busy professionals outside the UK)
Geographic Reach Multiple continents/international 
Policy Influence Type Influenced training of practitioners or researchers
Impact Course mirrors my earlier successful release of the two face-to-face LSHTM Infectious Disease Modelling courses and an Introductory Infectious Disease Modelling book (2010). As with the earlier courses and the book, the course is accompanied by extensive exercises and training materials designed to enable students and public health professionals to interpret and use mathematical modelling in their day to day practice. The conversion of this material to Distance Learning format will enable
 
Description WHO/South African Department of Health Tuberculosis Meeting
Geographic Reach Africa 
Policy Influence Type Gave evidence to a government review
Impact This and subsequent meetings lead to a change in the South Africa Govt's National Strategic Plan policy to include continuous Isoniazid Preventive Therapy (IPT) to HIV infected individuals. IPT greatly reduces mortality in HIV infected individuals. This will have a near immediate impact on survival / morbidity / quality of life in HIV+ South Africans.
 
Description Aeras project grant
Amount $150,000 (USD)
Organisation Aeras 
Sector Charity/Non Profit
Country Global
Start 10/2012 
End 03/2013
 
Description Aeras studentship grant
Amount $150,000 (USD)
Organisation Aeras 
Sector Charity/Non Profit
Country Global
Start 06/2013 
End 12/2016
 
Description Bill and Melinda Gates Foundation: Global Health: Tuberculosis
Amount $2,000,000 (USD)
Funding ID OPP1110334 
Organisation Bill and Melinda Gates Foundation 
Sector Charity/Non Profit
Country United States
Start 06/2014 
End 09/2016
 
Description Bill and Melinda Gates Foundation: Global Health: Tuberculosis
Amount $2,300,000 (USD)
Funding ID OPP1084276 
Organisation Bill and Melinda Gates Foundation 
Sector Charity/Non Profit
Country United States
Start 04/2014 
End 12/2015
 
Description Bill and Melinda Gates Foundation: Global Health: Tuberculosis
Amount $439,000 (USD)
Funding ID 21675 
Organisation Bill and Melinda Gates Foundation 
Sector Charity/Non Profit
Country United States
Start 06/2012 
End 11/2013
 
Description CR-UK
Amount £309,444 (GBP)
Organisation Cancer Research UK 
Sector Charity/Non Profit
Country United Kingdom
Start 07/2011 
End 06/2014
 
Description EU FP7
Amount £264,107 (GBP)
Funding ID 242061 
Organisation European Commission 
Department Seventh Framework Programme (FP7)
Sector Public
Country European Union (EU)
Start 01/2010 
End 01/2013
 
Description Project grant awarded by MRC/NIHR Methodology Research Panel
Amount £640,102 (GBP)
Funding ID MR/J005088/1 
Organisation Medical Research Council (MRC) 
Sector Academic/University
Country United Kingdom
Start 04/2012 
End 03/2015
 
Description TB Alliance project grant
Amount $350,000 (USD)
Organisation The Global Alliance for TB Drug Development 
Sector Charity/Non Profit
Country Global
Start 08/2012 
End 09/2013
 
Description USAID TB Treat Grant
Amount $1,499,000 (USD)
Funding ID GHN-A-OO-08-00004-00 
Organisation United States Agency for International Development 
Sector Public
Country United States
Start 04/2014 
End 03/2016
 
Description United States President's Emergency Plan for AIDS Relief (PEPFAR)
Amount $248,747 (USD)
Funding ID U2GPS0008111 
Organisation United States President's Emergency Plan for AIDS Relief 
Sector Public
Country United States
Start 04/2012 
End 03/2013
 
Description WHO
Amount $10,000 (USD)
Organisation World Health Organization (WHO) 
Sector Public
Country Global
Start 03/2013 
End 07/2013
 
Title New statistical method for Respondent Driven Sampling 
Description We created a new statistical analysis method that uses data collected from recruiters in RDS studies to reduce bias. This technique has been shared by publication. 
Type Of Material Data analysis technique 
Year Produced 2013 
Provided To Others? Yes  
Impact None yet 
URL http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0078402
 
Title New user-friendly country-level modelling tool for TB-HIV control projections and costings 
Description We created a user-friendly tool (a mathematical model) for TB-HIV control projections and costing. This tool is for use by country-level TB/HIV policy makers for decision making on TB control strategies and costing. It has been used in workshops at Global level by UNAIDS, the Global Fund and WHO, and at country level in South Africa, Viet Nam, Ghana, Nigeria. 
Type Of Material Computer model/algorithm 
Year Produced 2013 
Provided To Others? Yes  
Impact It was rolled out globally in 2015. So far it has been used by my group to update the Sudan, Bangladesh and Vietnam National Strategic Plan in 2013/4 (in Sudan, a move to more decentralized provision of TB patient care), and in Ghana, Nigeria. It will be used in about ~5 more high TB burden countries in 2016. 
URL http://www.avenirhealth.org/software-spectrum
 
Description Empirical evaluation of RDS in rural Uganda 
Organisation MRC/UVRI Uganda Research Unit on AIDS
Country Uganda 
Sector Public 
PI Contribution PI of research project. Wrote protocol. Trained staff. Supervised fieldwork and research staff. Analysed data. Led publication drafting.
Collaborator Contribution The fieldwork I conducted in Uganda relied critically on the research infrastructure of this MRC Unit, including access to data, equipment and facilities and training of staff.Significant intellectual input into research designSignificant intellectual input into research designAdvice on RDS fieldwork
Impact Dissemination of results to participants in research Multidisciplinary: Epidemiology, Statistics, Mathematics, Social Science.
Start Year 2009
 
Description Empirical evaluation of RDS in rural Uganda 
Organisation Tulane University
Department School of Public Health Tulane
Country United States 
Sector Academic/University 
PI Contribution PI of research project. Wrote protocol. Trained staff. Supervised fieldwork and research staff. Analysed data. Led publication drafting.
Collaborator Contribution The fieldwork I conducted in Uganda relied critically on the research infrastructure of this MRC Unit, including access to data, equipment and facilities and training of staff.Significant intellectual input into research designSignificant intellectual input into research designAdvice on RDS fieldwork
Impact Dissemination of results to participants in research Multidisciplinary: Epidemiology, Statistics, Mathematics, Social Science.
Start Year 2009
 
Description Empirical evaluation of RDS in rural Uganda 
Organisation University College London
Department Division of Infection and Immunity
Country United Kingdom 
Sector Academic/University 
PI Contribution PI of research project. Wrote protocol. Trained staff. Supervised fieldwork and research staff. Analysed data. Led publication drafting.
Collaborator Contribution The fieldwork I conducted in Uganda relied critically on the research infrastructure of this MRC Unit, including access to data, equipment and facilities and training of staff.Significant intellectual input into research designSignificant intellectual input into research designAdvice on RDS fieldwork
Impact Dissemination of results to participants in research Multidisciplinary: Epidemiology, Statistics, Mathematics, Social Science.
Start Year 2009
 
Description Empirical evaluation of RDS in rural Uganda 
Organisation University of Cambridge
Department Department of Veterinary Medicine
Country United Kingdom 
Sector Academic/University 
PI Contribution PI of research project. Wrote protocol. Trained staff. Supervised fieldwork and research staff. Analysed data. Led publication drafting.
Collaborator Contribution The fieldwork I conducted in Uganda relied critically on the research infrastructure of this MRC Unit, including access to data, equipment and facilities and training of staff.Significant intellectual input into research designSignificant intellectual input into research designAdvice on RDS fieldwork
Impact Dissemination of results to participants in research Multidisciplinary: Epidemiology, Statistics, Mathematics, Social Science.
Start Year 2009
 
Description HIV Modelling Consortium 
Organisation Imperial College London
Department Faculty of Medicine
Country United Kingdom 
Sector Academic/University 
PI Contribution Intellectual input
Collaborator Contribution Intellectual input
Impact Group funding: TB Alliance and Aeras project grants Publications Research ideas
Start Year 2012
 
Description TB Diagnostics Forum Modelling Workgroup 
Organisation Amsterdam Institute for Global Health and Development (AIGHD)
Country Netherlands 
Sector Private 
PI Contribution Intellectual input to discussions on characteristics of desired target product profiles for new diagnostics
Collaborator Contribution JHU leads the working group. AIGHD provides scientific input.
Impact Publications. Target Product Profiles of new diagnostics.
Start Year 2012
 
Description TB Diagnostics Forum Modelling Workgroup 
Organisation Johns Hopkins Medicine
Country United States 
Sector Hospitals 
PI Contribution Intellectual input to discussions on characteristics of desired target product profiles for new diagnostics
Collaborator Contribution JHU leads the working group. AIGHD provides scientific input.
Impact Publications. Target Product Profiles of new diagnostics.
Start Year 2012
 
Description TB Modelling and Analysis Consortium 
Organisation Bill and Melinda Gates Foundation
Country United States 
Sector Charity/Non Profit 
PI Contribution Intellectual and meeting organisational input. This consortium funds 50% of my time and 100% of two of my group members (1 research, 1 admin).
Collaborator Contribution Has resulted in significant intellectual and in-kind research time of many other research groups input to my groups research (e.g. Global TB Targets work was a collaboration of 11 international research groups contributing results to this research question, largely unfunded).
Impact Huge amount of outputs, please see other sections of report Publications in Modelling research agenda, TB Diagnostics Impact on Policy, Govt Budgets, and Research Priorities in South Africa
Start Year 2012
 
Description TB Modelling and Analysis Consortium 
Organisation Centers for Disease Control and Prevention (CDC)
Country United States 
Sector Public 
PI Contribution Intellectual and meeting organisational input. This consortium funds 50% of my time and 100% of two of my group members (1 research, 1 admin).
Collaborator Contribution Has resulted in significant intellectual and in-kind research time of many other research groups input to my groups research (e.g. Global TB Targets work was a collaboration of 11 international research groups contributing results to this research question, largely unfunded).
Impact Huge amount of outputs, please see other sections of report Publications in Modelling research agenda, TB Diagnostics Impact on Policy, Govt Budgets, and Research Priorities in South Africa
Start Year 2012
 
Description TB Modelling and Analysis Consortium 
Organisation Harvard University
Department Harvard T.H. Chan School of Public Health
Country United States 
Sector Academic/University 
PI Contribution Intellectual and meeting organisational input. This consortium funds 50% of my time and 100% of two of my group members (1 research, 1 admin).
Collaborator Contribution Has resulted in significant intellectual and in-kind research time of many other research groups input to my groups research (e.g. Global TB Targets work was a collaboration of 11 international research groups contributing results to this research question, largely unfunded).
Impact Huge amount of outputs, please see other sections of report Publications in Modelling research agenda, TB Diagnostics Impact on Policy, Govt Budgets, and Research Priorities in South Africa
Start Year 2012
 
Description TB Modelling and Analysis Consortium 
Organisation Intellectual Ventures
Country United States 
Sector Private 
PI Contribution Intellectual and meeting organisational input. This consortium funds 50% of my time and 100% of two of my group members (1 research, 1 admin).
Collaborator Contribution Has resulted in significant intellectual and in-kind research time of many other research groups input to my groups research (e.g. Global TB Targets work was a collaboration of 11 international research groups contributing results to this research question, largely unfunded).
Impact Huge amount of outputs, please see other sections of report Publications in Modelling research agenda, TB Diagnostics Impact on Policy, Govt Budgets, and Research Priorities in South Africa
Start Year 2012
 
Description TB Modelling and Analysis Consortium 
Organisation Johns Hopkins University
Department Johns Hopkins Bloomberg School of Public Health
Country United States 
Sector Academic/University 
PI Contribution Intellectual and meeting organisational input. This consortium funds 50% of my time and 100% of two of my group members (1 research, 1 admin).
Collaborator Contribution Has resulted in significant intellectual and in-kind research time of many other research groups input to my groups research (e.g. Global TB Targets work was a collaboration of 11 international research groups contributing results to this research question, largely unfunded).
Impact Huge amount of outputs, please see other sections of report Publications in Modelling research agenda, TB Diagnostics Impact on Policy, Govt Budgets, and Research Priorities in South Africa
Start Year 2012
 
Description TB Modelling and Analysis Consortium 
Organisation World Health Organization (WHO)
Department Department of Control of Neglected Tropical Diseases
Country Global 
Sector Public 
PI Contribution Intellectual and meeting organisational input. This consortium funds 50% of my time and 100% of two of my group members (1 research, 1 admin).
Collaborator Contribution Has resulted in significant intellectual and in-kind research time of many other research groups input to my groups research (e.g. Global TB Targets work was a collaboration of 11 international research groups contributing results to this research question, largely unfunded).
Impact Huge amount of outputs, please see other sections of report Publications in Modelling research agenda, TB Diagnostics Impact on Policy, Govt Budgets, and Research Priorities in South Africa
Start Year 2012
 
Description Training public health professionals in Infectious Disease Modelling 
Organisation Public Health England
Country United Kingdom 
Sector Public 
PI Contribution Wrote book and modelling courses. Run courses each year.
Collaborator Contribution Wrote book and modelling courses. Run courses each year.
Impact Published book used for training public health researchers in Infectious Disease Modelling. Multidisciplinary: Epidemiology, Demography, Statistics and Mathematics.
Start Year 2006
 
Title New user-friendly country-level tool for TB-HIV control projections and costings 
Description We created a user-friendly tool (a mathematical model) for TB-HIV control projections and costing. This tool will be freely available for download by country-level TB/HIV policy makers for decision making on TB control strategies and costing in 2015. It has been used in workshops run by UNAIDS, the Global Fund, WHO and at country level. 
IP Reference  
Protection Copyrighted (e.g. software)
Year Protection Granted 2013
Licensed Yes
Impact I was released globally in 2015. So far used to update Sudan, Bangladesh and Vietnam National Strategic Plan in 2013/4 (in Sudan: it led to a move to more decentralized provision of TB patient care), and in South Africa, Ghana and Nigeria. It will be used in about ~5 more high TB burden countries in 2016.
 
Title History matching of complex agent based computer models using emulation 
Description The developed method allows the calibration of multi-input, multi-output agent based computer models of high complexity. The method is based on a statistical approximation of the computer model, called the emulator, and tries to identify regions of the input space that are likely to lead to a match between the model's outputs and the calibration data. The computational efficiency of the emulator makes this method very applicable to computer models with long running times. 
Type Of Technology Software 
Year Produced 2013 
Open Source License? Yes  
Impact None yet 
URL http://cmmid.lshtm.ac.uk/mrccalib/
 
Title New user-friendly country-level modelling tool for TB-HIV control projections and costings 
Description We created a user-friendly tool (a mathematical model) for TB-HIV control projections and costing. This tool is for use by country-level TB/HIV policy makers for decision making on TB control strategies and costing. It has been used in workshops run by UNAIDS, the Global Fund and WHO over the coming years. 
Type Of Technology Software 
Year Produced 2013 
Open Source License? Yes  
Impact It was released globally in 2015. So far used to update the Government of Sudan, Bangladesh and Vietnam National Strategic Plan in 2013/4 (in Sudan, a move to more decentralized provision of TB patient care), South Africa, Ghana and Nigeria. It will be used in ~5 more high TB burden countries in 2016. 
URL http://www.avenirhealth.org/software-spectrum
 
Company Name Avenir Health 
Description Futures Institute, founded in 2006, is a global health organization that works to enhance social and economic development by providing tools and technical assistance in policy, planning, resource allocation and evaluation. In particular, we focus on developing and implementing demographic, epidemiological and costing models for long-range planning to assist with setting goals, strategies, and objectives. We assist in both developing and implementing programs in HIV/AIDS, reproductive health, maternal health and other programming areas. We work with government agencies, foundations, corporations, and nongovernmental organizations around the world. Areas of program concentration include family planning and reproductive health, maternal and child health, the prevention and treatment of HIV/AIDS, and infectious diseases. With staff based in the United States and Africa, we work collaboratively with our in-country counterparts to improve policies and programs that address population issues, reproductive health, HIV/AIDS, infectious diseases, and maternal and child health. 
Year Established 2006 
Impact Impacts are many and varied across a variety of health sectors. Impacts that my (Tuberculosis) work with them has supported includes: 1) generating country-level TB/HIV estimates for the WHO report 2013 and 2014, 3) Generating evidence for the STOPTB/WHO Tuberculosis Global Plan (2015) - global resource needs estimates, that are used to motivate for funding from international partners (Gates, Global Fund, ...) 3) Futures working with countries to develop TB/HIV National Strategic Plans in 3+ countries globally, affecting governmental TB/HIV strategies and resource allocation within these 3 countries. This is an active and growing collaboration and much more activity will happen over the next 12 months.
Website http://www.avenirhealth.org/
 
Description Dissemination of results to participants in research 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach Local
Primary Audience Participants in your research and patient groups
Results and Impact About 20 community leaders representing the villages surveyed in the Empirical RDS evaluation attended a dissemination meeting.
Led to many questions and discussion of results.

Community leaders were very interested in results and the session increased understanding of RDS and (in conjunction with on-going community activities by the MRC Uganda Unit) increased motivation for engaging in this and other research activities.
Year(s) Of Engagement Activity 2010
 
Description TB vaccines film documentary (International 2013) 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Policymakers/politicians
Results and Impact I was interviewed and included in 2 short easily assessable films made on need for TB vaccine research. Films show internationally to public, policy, funder and academic audiences.

Films have been shown to parliamentarians, policy makers, funder (eg European Investment Bank) and the general public. Has increased support for TB vaccine development at a time when a negative trial was announced and cuts were expected.
Year(s) Of Engagement Activity 2013
URL http://www.aeras.org/exposed
 
Description TB vaccines press release (International 2013) 
Form Of Engagement Activity A press release, press conference or response to a media enquiry/interview
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Media (as a channel to the public)
Results and Impact Led to reporting by 5 news organizations internationally

None
Year(s) Of Engagement Activity 2013
 
Description TB vaccines press release (International 2013) 
Form Of Engagement Activity A press release, press conference or response to a media enquiry/interview
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Media (as a channel to the public)
Results and Impact Led to interview with leading US newswire service and story reported in 100s of newspapers and news outlets worldwide, mostly in the US

The potential damage that a negative finding from a vaccine trial was mitigated to some (unmeasured) extent and hopefully public support for TB vaccine trials was maintained.
Year(s) Of Engagement Activity 2013