Who Guideline on Estimation of Residual Risk of Hiv, Hbv
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1 2 3 WHO/BS/2016.2283 4 ENGLISH ONLY 5 6 WHO GUIDELINE ON ESTIMATION OF RESIDUAL RISK 7 OF HIV, HBV OR HCV INFECTIONS VIA CELLULAR 8 BLOOD COMPONENTS AND PLASMA 9 NOTE: 10 This document has been prepared for the purpose of inviting comments and suggestions on the 11 proposals contained therein, which will then be considered by the Expert Committee on Biological 12 Standardization (ECBS). Publication of this early draft is to provide information about the proposed 13 WHO Guideline on estimation of residual risk of HIV, HBV or HCV infections via cellular blood 14 components and plasma, to a broad audience and to improve transparency of the consultation process. 15 The text in its present form does not necessarily represent an agreed formulation of the Expert 16 Committee. Written comments proposing modifications to this text MUST be received by 17 16th September 2016 in the Comment Form available separately and should be addressed to the 18 World Health Organization, 1211 Geneva 27, Switzerland, attention: Department of Essential 19 Medicines and Health Products (EMP). Comments may also be submitted electronically to the 20 Responsible Officer: Dr C Micha Nübling at email: [email protected]. 21 The outcome of the deliberations of the Expert Committee on Biological Standardization will be 22 published in the WHO Technical Report Series. The final agreed formulation of the document will be 23 edited to be in conformity with the "WHO style guide" (WHO/IMD/PUB/04.1). 24 © World Health Organization 2016 25 All rights reserved. Publications of the World Health Organization can be obtained from WHO Press, World Health 26 Organization, 20 Avenue Appia, 1211 Geneva 27, Switzerland (tel.: +41 22 791 3264; fax: +41 22 791 4857; e-mail: 27 [email protected]). 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WHO/residual risk/Draft/1 June 2016 Page 3 1 SCHEDULE FOR THE PROPOSED ADOPTION PROCESS OF DOCUMENT 2 3 WHO Guideline on Estimation of Residual Risk of HIV, HBV or HCV Infections via 4 Cellular Blood Components and Plasma 5 Endorsement of the “residual risk guideline” project by the WHO 15.-19.10.2012 Expert Committee on Biological Standardization (ECBS), based on requests from low- and middle-income countries aiming to use recovered plasma for manufacture of plasma derived medicinal products Discussions on outline and necessary elements of the guidance 09.-12.06.2014 document at the “WHO Workshop on Blood Testing and Risk Assessment as part of GMP in blood establishments”, Jakarta, Indonesia Working group of experts in the fields of epidemiology and blood safety 17.-18.06.2015 testing; meeting at WHO HQ, Geneva, Switzerland Circulation of draft guideline among working group members and Aug / Sep 2015 international experts Presentation and discussion of draft guideline at the WHO AFRO 23.-25.09.2015 “Regional workshop on the development of regional strategy for blood safety and the establishment of national regulatory system for blood and blood products”, Cotonou, Benin Presentation and discussion of draft guideline at the WHO Expert 12.-16.10.2015 Committee on Biological Standardization (ECBS) Presentation and discussion of draft guideline at the Blood Regulator 15.10.2016 Network (BRN) Presentation and discussion of draft guideline at the “12th Arab 20.-23.11.2015 Transfusion Medicine Forum (ATMF), Cairo, Egypt Presentation and discussion of draft guideline at the WHO EMRO 17.-19.05.2016 “Regional Meeting of Directors of National Blood Transfusion Services“, Tunis, Tunisia Presentation and discussion of draft guideline at the “IPFA / PEI 23rd 25.-26.05.2016 International Workshop on Surveillance and Screening of Blood Borne Pathogens”, Lisboa, Portugal Circulation of draft guideline among working group members and Apr – Jun 2016 international experts Circulation of final draft guideline version for public consultation Jun – Sep 2016 Consolidation of comments received and review of feedback Oct 2016 Presentation to the WHO Expert Committee on Biological 17.-21.10.2016 Standardization for adoption Any other follow-up action as required 6 WHO/residual risk/Draft/1 June 2016 Page 4 1 Executive Summary 2 This guideline advises on estimation of the residual risk of HIV, HBV or HCV being present 3 in cellular blood components and plasma. This estimation has implications for the safety of 4 non- (or incompletely) inactivated blood or plasma products. There are large differences in 5 the prevalence and incidence of viral infections in blood donors around the world. The impact 6 of these epidemiological differences on blood safety needs to be assessed together with the 7 sensitivity of the testing strategy applied. These estimations may be used for strategic 8 decisions on the choice of assays to interdict virus-positive blood and plasma units and as a 9 basis for cost benefit analysis of different testing scenarios most suitable in the region. The 10 factors influencing the risk of virus transmissions by blood components are described as well 11 as simple mathematical formulas to calculate its probability. Similarly, the probability and 12 potential level of viral contamination of plasma pools used for manufacture of plasma derived 13 medicinal products can be calculated and subsequently the infectivity risk of plasma products 14 can be estimated in relation to the inactivation and reduction capacity of the manufacturing 15 process. Currently, recovered plasma from whole blood donations is often not used for 16 plasma fractionation because of the potential virus risks and quality concerns. It is hoped that 17 this document can help in rationalising decision making on the use of plasma units for 18 fractionation on the basis of residual risk estimations. 19 Since the performance of assays is a key element in minimizing residual risk of blood 20 components and guaranteeing safety of plasma products, an annex to this guideline gives 21 advice on assessment of in vitro diagnostics in studies using specimen panels from the region. 22 This limited performance evaluation of new assays may be performed prior to acceptance of a 23 new blood screening assay in the country. 24 25 WHO/residual risk/Draft/1 June 2016 Page 5 1 Content Page no. 2 Glossary 6 3 Abbreviations 9 4 Introduction 10 5 (1) Course of HIV, HBV and HCV infections 10 6 (2) Residual risk origins 11 7 (3) Screening assay categories and diagnostic window periods 13 8 (4) Viral concentrations during diagnostic window 16 9 (5) Confirmation of reactive screening results 17 10 (6) Virus epidemiology of donor populations 17 11 (7) Estimation of incidence and window period modelling of risks 18 12 (8) Residual risks 22 13 References 23 14 Annex 1 Targeted evaluation of new blood screening assays 28 15 Annex 2 Examples for estimation of residual risks 31 16 Achnowledgment 34 17 18 WHO/residual risk/Draft/1 June 2016 Page 6 1 Glossary 2 Analytical sensitivity: the smallest amount of the target marker that can be precisely 3 detected by an assay; it may be expressed as the limit of detection and is often determined by 4 testing limiting dilutions of a biological reference preparation 5 Apheresis: the process by which one or more blood components are selectively obtained 6 from a donor by withdrawing whole blood, separating it by centrifugation and/or filtration 7 into its components, and returning those not required to the donor. The term ‘plasmapheresis’ 8 is used for a procedure dedicated specifically to the collection of plasma.