Serial testing is the minimum that can be used. Parallel testing is effective but costly. Never give out results with one screening test, as there is the risk of giving out some false positive results. Initial (screening) tests must be sensitive, while the confirmatory test must be specific.
Module 1: Overview of HIV Infection Unit 01.04: Laboratory Diagnosis and Monitoring of HIV Infection
Developed by UNIADS/WHO for use in confirming initial HIV positive tests
maximizes accuracy while minimizing high cost associated with Western Blot but retaining similar predictive values to Western blot and others.
Three testing strategies recommended by UNAIDS/WHO
Strategy used depends on purpose of the test and the prevalence of HIV in the population
The strategy used works on the principle of using two screening tests either in parallel or sequentially
Report sensitive Consider +ve A +ve -ve specific B +ve -ve sensitive A +ve -ve Report Indeterminate Report sensitive C +ve -ve + - - Low risk A +ve -ve sensitive specific B +ve -ve Report Report TRANSFUSION TRANSFUSION SURVEILLANCE DIAGNOSIS DIAGNOSIS I II III WHO HIV antibody testing strategies + - + High risk Sensitivity >97% Specificity >95% SERIAL TESTING PARALLEL TESTING