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Organization and Planning of HIV Testing for Surveillance Purposes Dr G. Vercauteren Diagnostics and Laboratory Technology Essential Health Technologies World Health Organization. National HIV prevalence surveys.
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Organization and Planning of HIV Testing for Surveillance Purposes Dr G. Vercauteren Diagnostics and Laboratory Technology Essential Health Technologies World Health Organization
National HIV prevalence surveys • Obtaining an accurate estimate of the number of people infected with HIV in a country or region is important for the purpose of evaluation, programme planning and advocacy. • Large scale national surveys to need to be carefully planned and conducted to ensure cost-effective use of resources.
National HIV prevalence surveys • Population-based surveys • Household (men, women, children) • Rural -Urban • Sentinel surveillance • Population groups • Pregnant women • Sex workers • Migrant populations • Police-army • prisoners
Planning a population based survey to measure HIV prevalence (1) • Survey objectives • Design of the survey • Survey population, geographical area, timelines • Sampling method • Sampling units (households or individuals) Select catch area • Calculate sample size • Specify data to be included • demographic data • sexual behaviour data, knowledge related to HIV and reproductive health • other biomarkers • Design questionnaire for data collection
Planning a population based survey to measure HIV prevalence (2) • HIV testing • Plan the survey budget • Ethical principles and approval • Design informed consent procedures • Plan the survey operations • Staff organization • Mobilization • Prepare manuals and pretest questionnaires and HIV testing procedures • Train staff : before field work begins
Planning a surveillance survey : some laboratory issues • Survey population: Inclusion of children aged 0 – 14 years ? • Testing for other biomarkers • Anemia • Syphilis ; other sexually transmissible infections • incidence • Approach for HIV testing • Specimen type: blood, saliva, urine; DBS • Select specific assays & algorithm • Ability to distinguish between HIV-1 and HIV-2 • EIA and/or rapid test • Where will the testing take place • Quality assurance • Biosafety
Planning a surveillance survey : • Budget planning : • Estimate Nos of tests for screening, confirmation, do not forget to cost to pilot and QA • Training of all staff involved • Provision of VCT (referal) • Ethical considerations • Do no harm, stigma, confidentiality ? • Participate in benefits (offer VCT, treatment ?) • Study procedures & risks • Voluntary nature of participation Ethical approval • Informed consent • Purpose & procedures • Risks & benefits • Protection of anonymity and/or confidentiality • Clear understandable language, opportunity to ask questions • Participation is voluntary (specimen type?)
Planning a surveillance survey : some laboratory issues • Planning survey operations • Staff organization • Define roles and responsibilities & workload • Supervisors, Interviewers, Testers, Data entry specialists • Mobilization : All relevant players • Preparing manuals and pretest them • How to collect; store and transport specimen • How to perform the testing • Assess procedures: • Is specimen type acceptable to the population • Are logistics in place for specimen collection, transport, verification and storage; • Training of staff • Train all staff involved • In particular if non-laboratory staff will collect specimens and/or carry out testing • Ethics and Confidentiality • Supervisors how to ensure quality of the processes ( strict labelling procedures, recording of issues) • Verification upon receipt in the laboratory
Conducting an HIV prevalence survey 1. Field operations The aim of fieldwork is to collect high-quality information and biological specimens from individuals whilst adhering to the sampling design.
Conducting an HIV prevalence survey 2. HIV testing a) Collecting, handling, processing and tracking specimens • Biological specimens should be clearly labelled with a survey code, e.g a unique identification number assigned at the time of collection. • The survey code will link the test result of the specimen to other survey data • Storage of specimens depend on the type of specimen • Serum: keep at 4°C for upto 7 days, or at -20°C for longer periods • DBS: keep at room temp in plastic bag with desicant for max 30 days or at 4°C upto 3 months or at -20°C for longer periods • Systematic procedures to reduce transcriptional errors • DBS, avoid contamination, eluate properly, be meticulous.
HIV testing strategy for surveillance (unlinked) Strategy II A11 A1- Report negative A1+ A21 A1+A2- Report negative2 A1+A2+ Report positive2 1 Assay A1, A2 represent test results from 2 different assays 2 Report: result may be reported negative for surveillance purposes
Conducting an HIV prevalence survey b) Ensure confidentiality and anonymity • Staff taking specimens should not do the testing • Databases need to be password protected with restricted access to HIV test results, lock up computers • Register of HIV test results and back up files need to be locked up (limited access) • Before merging test results with other survey data, all personal information should be removed c) Providing test results and VCT 3. Data management • Data should be entered twice by two independent entry staff to minimize error • HIV data should be entered separately 4: Unlinked versus Linked test results
HIV testing approaches • Unlinked anonymous testing(without informed consent) • Testing of unlinked specimens collected for other purposes • No personal identifiers or names obtained, no counselling required • Coded specimens • Unlinked anonymous testing(with informed consent) • Testing of unlinked specimens collected solely for surveillance purposes • Informed consent required • No personal identifiers or names obtained, no counselling required • Coded specimens
HIV testing approaches • Linked confidential testing(with informed consent) • Informed consent and pretest & posttest counselling required • Personal identifiers or names obtained, • Coded specimens; code linked to personal indentifying information • Linked anonymous testing(with informed consent) • Informed consent and pretest & posttest counselling required • Informed consent required • No personal identifiers or names obtained • Coded specimens; code given to patient/client so only patient can link him/herself to results
Quality Assurance and safety • Standard operating procedures need to be followed: • Pre-analytical phase • Analytical phase • Post analytical phase • Quality control samples • Repeat testing of specimen in both assays in case of discordant results • Proficiency testing • Retesting of specimens • Statistical valid manner • In a timely manner • Proper handling and disposal of biohazardous waste needs to occur at each end of the day.
Re-test size to provide 95%confidence to detect at least 1 discrepancy with underlying error 1%_3%_5%
Re-test size to provide 99%confidence to detect at least 1 discrepancy with underlying error 1%_3%_5%
Diagnostics and Laboratory Technology (DLT) Team www.who.int/diagnostics_laboratory