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HIV Rapid Point-of-Care Testing Program

HIV Rapid Point-of-Care Testing Program. New POC Reactive Algorithm. HIV Seroconversion. Detection of HIV by Diagnostic Tests. Symptoms p24 Antigen HIV RNA HIV EIA* Western blot. 0 1 2 3 4 5 6 7 8 9 10. Weeks Since Infection.

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HIV Rapid Point-of-Care Testing Program

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  1. HIV Rapid Point-of-Care Testing Program New POC Reactive Algorithm

  2. HIV Seroconversion

  3. Detection of HIV by Diagnostic Tests Symptoms p24 Antigen HIV RNA HIV EIA* Western blot 0 1 2 3 4 5 6 7 8 9 10 Weeks Since Infection *3rd generation, IgM-sensitive EIA After Fiebig et al, AIDS 2003; 17(13):1871-9 *2nd generation EIA *viral lysate EIA * 4th generation Ag/Ab Combo

  4. Algorithms for HIV • Sequential testing to ensure highest possible sensitivity and specificity • Tests must have different scientific principles/ reagents • Original PHL algorithm for POC reactive samples HIV 1/2 EIA Screen Western blot confirm P24 Ag; Supp EIA Ind or both Advise Repeat Report HIV + Report Negative

  5. Current PHL Screening Assay • In 2010, PHL changed their screening assay from the 3rd Generation Antibody Assay – to a 4th Generation HIV 1/2 Antigen/Antibody Combination Assay. • At that time, PHL changed the algorithm for POC reactive samples HIV 1/2 EIA Ag/Ab Screen Report Negative Western blot confirm Ind Advise Repeat Report HIV +

  6. PHL Rational for New Algorithm • Combo Screen test now offers HIV antibody, HIV p24 antigen, IgM • No need for any additional testing for POC Reactives • Checked historical data (old algorithm) and did not find any true positives among POC R- PHL 3rd gen neg (n=123) • IgM is detected by 3rd gen assays so this is not new • Algorithm is missing the supplemental 3rd gen assay

  7. Concern • POC Reactive and PHL Screen Assay Non-reactive is a “Discordant” result • PHL Screen Assay (Ag/Ab) is an excellent test, but is not a confirmatory test. • International standards require additional testing for discordant results • Potential risk (small) that an HIV positive person would receive an HIV negative result

  8. Dilemma • The only suitable supplemental testing that could be done (NAAT) is not available in Ontario.

  9. Moving Forward • Beginning in September, 2013, PHL will attach a comment to all POC R, PHL Ag/Ab NR samples • “A repeat test is strongly recommended” (exact wording tbd) POC Reactive HIV 1/2 EIA Ag/Ab Screen Report Negative Western blot confirm Advise Repeat PHL will retain sample Ind Advise Repeat Report HIV +

  10. How to handle POC R, PHL Neg REPEAT POC Test – ASAP

  11. What PHL will do • PHL will retain the first POC R, Ag/Ab NR sample • If the second POC is Reactive and two samples are received: • PHL will do Ag/Ab screen test as usual • If Reactive, they will follow their usual confirmatory algorithm and report • If Non-reactive, they will report it as HIV negative • In both cases, the first and second serum samples, and the lavender topped tube will be sent to the HIV National Reference Laboratory for additional testing (NAAT, plus other supplemental HIV tests) • Results may take 1-2 months.

  12. What sites should do:Repeat POC when client returns for results • POC Reactive • Counsel likely false reactive, but additional testing is required • Collect red and lavender vacutainers • Complete req with all details (prev lab number, risk, etc.,) • Attach purple sticker and pink sticker • Advise PHL and AIDS Bureau • POC Non-reactive • Counsel as negative (with usual caveats) • No need to do further PHL testing • Complete req with all details (prev lab number, risk, etc.,) • Attach purple sticker and green sticker • Advise AIDS Bureau

  13. Additional Discussion • NRL, PHL and AIDS Bureau will monitor the outcomes for POC R, Ag/AbNonR clients • When the new algorithm has been validated we will be able to stop the additional testing. • Anticipate approximately 20 cases per year – so very rare occurrence. • AIDS Bureau will send out a program update and host a webinar to advise sites of these changes • In the meantime, please call AIDS Bureau if you have any POC R, PHL Negative cases.

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