Transcript 2nd generation HIV surveillance

Key concepts in the 2nd
generation HIV/ AIDS
surveillance
“Second Generation HIV Surveillance” (SGHS)
Content of the presentation
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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
surveillance
STI
surveillance
AIDS
reporting
behavioural
surveillance
Data management
HIV estimates and projections
Use of data for action
Source: WHO
2nd HIV surv.: data collection methods
“RISK”
SURVEILLANCE
HIV INCIDENCE
SURVEILLANCE
HIV PREVALENCE
SURVEILLANCE
VIRAL LOAD
“WINDOW”
PERIOD
INFECTION
AIDS CASE
SURVEILLANCE
AIDS
DEATHS
HIV ANTIBODIES
ASYMPTOMATIC PERIOD
HIV ILLNESS
or AIDS
DEATH
HIV infections newly diagnosed by transmission group
1994-2002, western Europe*
Persons infected
heterosexually (HC)
Cases
6000
5000
HC from country
with generalised
epidemic
Homo/bisexual men
4000
3000
Update at 30 June 2003
2000
Risk not reported
1000
Injecting drug users
0
1994
1995
1996
1997
1998
1999
2000
2001
2002
Year of report
* Belgium, Denmark, Finland, Germany, Greece, Iceland
Luxembourg, Norway, Sweden, Switzerland, United Kingdom
EuroHIV
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
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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 subpopulations at risk of
HIV infection
Pre-surveillance
assessments using
rapid/qualitative techniques
Plan for next round
of surveillance
IDUs?
MSM?
SWs?
All?
Sub-groups?
Use data to strategically
target interventions
and/or monitor ongoing
intervention effects
Reach consensus on
groups to include in
surveillance
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?