Key concepts in the 2nd generation HIV/ AIDS surveillance “Second Generation HIV Surveillance” (SGHS) Content of the presentation • Objectives of surveillance systems for policy making • Methods and data sources • From data to information • Principles underlying 2nd generation HIV surveillance • Components in low level and concentrated epidemics Rationale for Disease Surveillance • Public health importance of disease ? • Can public health action be taken ? • Are relevant data easily available ? • Is it worth the effort (money, human resources)? What are the objectives of surveillance ? Aims of surveillance to give up to date information on the state of infectious diseases: for control and prevention to assist in policy making to improve epidemiological research Surveillance: “data for action” Surveillance is the ongoing systematic collection, collation, analysis and interpretation of data; and the dissemination of information to those who need to know in order that action may be taken 2nd Generation HIV Surveillance, main objective: To monitor HIV and high-risk behaviour trends over time in order to provide essential data needed for the development of interventions and the evaluation of their impact = to provide a more comprehensive understanding of the HIV epidemic effective coordination between surveillance and prevention programmes needed 2nd generation HIV surveillance HIV STI surveillance surveillance AIDS behavioural reporting surveillance Data management HIV estimates and projections Use of data for action Source: WHO 2nd HIV surv.: data collection methods “RISK” HIV INCIDENCE HIV PREVALENCE AIDS CASE AIDS SURVEILLANCE SURVEILLANCE SURVEILLANCE SURVEILLANCE DEATHS VIRAL LOAD HIV ANTIBODIES “WINDOW” PERIOD ASYMPTOMATIC PERIOD HIV ILLNESS INFECTION or AIDS DEATH HIV infections newly diagnosed by transmission group 1994-2002, western Europe* Cases Persons infected 6000 heterosexually (HC) 5000 HC from country with generalised 4000 epidemic Homo/bisexual men 3000 2000 Risk not reported Update at 30 June 2003 1000 Injecting drug users 0 1994 1995 1996 1997 1998 1999 2000 2001 2002 Year of report EuroHIV * Belgium, Denmark, Finland, Germany, Greece, Iceland Luxembourg, Norway, Sweden, Switzerland, United Kingdom Epidemiologic Principles Underlying HIV Surveillance • HIV infections are not uniformly distributed in a population • HIV infection enters into different geographic areas and populations at different times, and spreads at different rates #3-2-10 HIV/AIDS Surveillance in the First Decade of the Epidemic • Mainly HIV sentinel surveillance and AIDS reporting • Did not make best use of other data sources • Provided poor early warning • Ignored at-risk subpopulations Second-Generation HIV Surveillance • Developed by the WHO and UNAIDS as a response to the increasing complexity of the HIV epidemic • Comprises of more sophisticated surveillance activities and provides a more comprehensive understanding of epidemic trends • Improves effectiveness of control and prevention efforts • HIV/AIDS surveillance is one of the key elements of any HIV/AIDS programme • Tailor surveillance to local situation • Target locally relevant groups and behaviours • Focus on new infections/ risk – maximum impact • Importance of quality: critically examine quality of our systems Importance for planning programmatic responses • Get ahead of the epidemic instead of playing “catch-up” State of HIV Epidemics Low Level Epidemics HIV <5% in all sub population with high risk behaviour Concentrated Epidemics HIV >5% among in any subpopulation with high risk behaviour and < 1% among women attending antenatal clinic Generalized Epidemics HIV > 1% among women attending antenatal clinic (in general population) Source: WHO Patterns of HIV epidemics in the world Type of the epidemic Generalized Concentrated Low Level No Data Source: WHO AIDS case surveillance LIMITATIONS • Accuracy of information (under diagnosis) • Rate of notification (under reporting) • Delay on reporting • Different AIDS case definitions • Limited reporting from private sector Source: WHO Overview of HIV Surveillance • There are two general approaches to HIV surveillance: – HIV case reporting – HIV sero-surveillance • Surveillance activities can either be active or passive. #3-1-7 Quality of sero-surveillance systems Sero-surveillance system quality Fully implemented systems Some aspects of a fully implemented system Poor or non-functioning system Source: WHO Current Challenges in Eastern Europe • West – Maintain preventive behaviour – Promote access to diagnostic testing and care for infected individuals • Central – Maintain low level transmission • East – Control current epidemics in IDU – Prevent sexually transmitted HIV – Provide access to diagnostic testing and care for infected individuals STI Surveillance as Component of 2nd Generation HIV Surveillance – STI as a measure of HIV risk – Biologic and epidemiologic evidence that STI facilitate the spread of HIV – Role of STI treatment in prevention of HIV What is behavioural surveillance? • BSS is a monitoring and evaluation tool designed to systematically monitor trends in HIV risk behaviors over time in key target groups • BSS is carried out through a series of repeated cross-sectional surveys conducted at regular intervals on a national or regional scale Use of behavioural surveillance surveys (BSS) • Information: informs program designs and serves as an early warning system • Evaluation: provides documentation of behavior change over time (in response to interventions) • Triangulation: contributes to biological and behavioral surveillance systems to provide additional data for HIV/AIDS estimates and projections Note: Behavioral data does NOT draw a direct causal link between particular interventions and particular levels of behavior change Target populations for HIV surveillance in low and concentrated epidemics • Injecting drug users (IDUs) • Female and male sex workers (FSW, MSW) • Men who have sex with men (MSM) • Prisoners • TB patients • Men on the move (MOM, truckers) HIV/STI transmission dynamics at population level General population Bridging population High frequency transmitters HIV and behavioural surveys • Refusal rate is usually higher for HSS • Objectives of surveys are different – Sample sizes – Groups may not overlap • HIV and not BSS – STI, ANC, TB • HIV and BSS – FSW, IDU, youth Sentinel sites for hard-to-reach populations – STD clinic (FSW, MSM) – Special clinic (FSW, MSM) – Drug treatment program, needle exchange program (IDU) – TB patients Sentinel sero-surveillance is the mainstay of HIV/AIDS surveillance in many developing countries Criteria for 2nd generation surveillance • Surveillance systems should be appropriate to the epidemic state and dynamic • Surveillance systems should use resources efficiently, focusing on populations at particular risk • Behavioural data should be used to guide biological data collection and explain trends in HIV infection Source: WHO 2nd generation HIV surveillance • Limitations of (sexual) behaviour data – Specificity and sensitivity of questionnaires – Cost and complexity of quality studies • Adding STI data could improve on both specificity and sensitivity by using “objective” laboratory tests • Advantages of “triangulation” (HIV, STI & behavioural data) • Ability to detect change • More timely for prevention Source: WHO 2nd HIV surveillance: providing key answers HIV Questions for surveillance epidemic • Any risk behaviour leading to HIV epidemic? Low-level • Sub-populations with risk behaviour? and • Sub-populations: size? HIV prevalence? Behaviours? Concentrated • Links between these sub-populations and general pop.? • What are the trends in HIV infection? • Do trends in behaviour explain trends in HIV prevalence? Generalized • Impact of interventions on risk behaviours? • Impact of HIV epidemic on individual, family and country? The full surveillance cycle Identify sub- Pre-surveillance populations at risk of assessments using HIV infection rapid/qualitative techniques Plan for next round of surveillance IDUs? MSM? SWs? Reach consensus on All? groups to include in Sub-groups? surveillance Use data to strategically target interventions and/or monitor ongoing intervention effects Conduct surveillance Strategic Goals of HIV prevention programmes • Reduce the transmission – Lowering the risk of STI/HIV transmission – targeted interventions • Reduce the vulnerability – Prolonging and improving the quality of life – treatment and care of STI/HIV and related morbidity and disability • Reduce the impact – Promoting enabling health sector policies and institutional environments Have data. Now what? Key questions • How well are we meeting the 2nd generation goals in Croatia? • Are serosurveillance systems being tailored to the local situation? • Are we collecting the appropriate biological and behavioural data for the state of low-level epidemics?
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