Technical Specifications Series for submission to …...Technical Specifications Series for...

Technical Specifications Series

for submission to WHO Prequalification – Diagnostic

Assessment

TSS-14

Immunoassays to detect hepatitis

B virus surface antigen (draft)

DRAFT FOR COMMENT (01 DECEMBER 2019): This is a draft intended for review by

Member States and all interested parties for the purpose of consultation on the draft text. The content

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Technical Specifications for submission to WHO Prequalification – Diagnostic Assessment: TSS 14

Immunoassays to detect hepatitis B surface antigen

Page | iii

Table of contents 34

Table of contents ........................................................................................................................ iii 35

Acknowledgements..................................................................................................................... iv 36

List of contributors ...................................................................................................................... iv 37

Abbreviations .............................................................................................................................. 1 38

A. Introduction ..................................................................................................................... 1 39

B. How to apply these specifications. .................................................................................... 2 40

C. Other guidance documents .............................................................................................. 2 41

D. Performance principles for WHO Prequalification ............................................................. 3 42

E. Table of requirements ...................................................................................................... 6 43

Part 1: Analytical Performance and Other Evidence (non-clinical evidence) ................................... 7 44

Part 2: Clinical Evidence ............................................................................................................. 20 45

Part 3: Evidence for performance of confirmatory (neutralisation) reagents, if provided .............. 24 46

F. Source documents .......................................................................................................... 26 47

48

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Acknowledgements 49

The document “Technical Specifications Series for submission to WHO Prequalification – 50 Diagnostic Assessment: Immunoassays to detect hepatitis B virus surface antigen” was 51 developed with support from the Bill & Melinda Gates Foundation. The document was 52 prepared in collaboration with R. J. S. Duncan, United Kingdom of Great Britain and 53 Northern Ireland; H. Bayer, Germany; D. Healy, U. Ströher, Prequalification Team – 54 Diagnostic Assessment, WHO, Geneva. This document was produced under the 55 coordination and supervision of U. Ströher and I. Prat, Prequalification Team – Diagnostic 56 Assessment, WHO, Geneva, Switzerland. 57

List of contributors 58

A technical consultation on WHO prequalification requirements for hepatitis B surface 59 antigen detection rapid diagnostic tests and other immunoassays, and hepatitis B virus 60 nucleic acid detection tests was held in Geneva, Switzerland from 22 to 23 October 2019. 61

Meeting participants: N. Almond, National Institute for Biological Standards and Control 62 (NIBSC), Hertfordshire, United Kingdom; A. Andonov, Ottawa, Canada; H.P.W. Bayer, 63 Weinheim, Germany; S. Best, Melbourne, Australia; R.J.S. Duncan, London, United 64 Kingdom; S. Kamili, Division of Viral Hepatitis, Centers for Disease Control and Prevention 65 (CDC), Atlanta, United States of America; J. Kress, Paul-Ehrlich-Institut, Langen, Germany; 66 L. Lewis, Instituto Oswaldo Cruz, Fundação Oswaldo Cruz, Ministério da Saúde, Rio de 67 Janeiro, Brazil; R. Luo, California, USA; T. Maponga, Stellenbosch University, South Africa; 68 T. Meehan, Clinton Health Access Initiative (CHAI), Boston, USA; S. Nick, Paul-Ehrlich-69 Institut, Langen, Germany; J. Parry, Middlesex, United Kingdom; K. Perry, Public Health 70 England (PHE), London, United Kingdom; E. Pirou, Médecins Sans Frontières, Amsterdam, 71 The Netherlands; B. Rewari, WHO South East Asia, New Delhi, India; J. Saldanha, Oakland, 72 USA; S. Schlottmann, Food and Drug Administration FDA, Maryland, USA 1 ; Kathlyn 73 Whitman, Food and Drug Administration FDA, Maryland, USA.2 74

WHO Secretariat: D. Healy; H. Mbunkah; A.L. Page; I. Prat; U. Ströher, Prequalification 75 Team – Diagnostic Assessment Group, Regulation of Medicines and other Health 76 Products; P. Easterbrook, Global Hepatitis Programme 77

1 Joined by teleconference 2 Joined by teleconference



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Abbreviations 78

ANA anti-nuclear antibodies 79

CV coefficient of variation 80

DBS dried blood spot specimens 81

DNA deoxyribonucleic acid 82

EDTA ethylenediaminetetraacetic acid 83

HAMA human anti-mouse antibody 84

HBV hepatitis B virus 85

HBsAg surface antigen of hepatitis B virus 86

HTLV Human T-lymphotropic virus 87

IFU instructions for use 88

IgG, IgM immunoglobulin G, M 89

IMDRF International Medical Device Regulators Forum 90

IVD in vitro diagnostic 91

LOD limit of detection 92

NAT nucleic acid amplification technology 93

ROC receiver operator characteristic 94

SD standard deviation 95

SLE systemic lupus erythematosus 96

TSS Technical Specification Series 97

WHO World Health Organization 98

A. Introduction 99

The purpose of this document is to provide technical guidance to in vitro diagnostic 100 (IVD) medical device manufacturers that intend to seek WHO prequalification of 101 qualitative immunoassays intended to detect surface antigen of hepatitis B 102 virus(HBsAg). 103

Quantitative immunoassays with a monitoring function are not included in the 104 scope of this TSS. The requirements for rapid diagnostic tests for the detection of 105 HBsAg are described in a separate TSS document (see TSS-13). 106

107

For the purpose of this document, the verbal forms used follow the usage described 108 below: 109

• “shall” indicates that the manufacturer is required to comply with the 110 technical specifications; 111

• “should” indicates that the manufacturer is recommended to comply with the 112 technical specifications, but it is not a requirement; 113

• “may” indicates that the technical specifications are a suggested method to 114 undertake the testing, but it is not a requirement. 115

116

A documented justification and rationale shall be provided by the manufacturer 117 when the WHO prequalification submission does not comply with the required 118 technical specifications outlined in this document. 119



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For WHO prequalification purposes, manufacturers shall provide evidence in 120 support of the clinical performance of an IVD to demonstrate that reasonable steps 121 have been taken to ensure that a properly manufactured IVD, being correctly 122 operated in the hands of the intended user, will detect the target analyte 123 consistently and fulfil its indications for use. 124

Where possible, WHO analytical and clinical performance study requirements are 125 aligned with published guidance, standards and/or regulatory documents. 126 Although references to source documents are provided, in some cases WHO 127 prequalification has additional requirements. 128

WHO prequalification requirements summarized in this document do not extend 129 to the demonstration of clinical utility, i.e. the effectiveness and/or benefits of an 130 IVD, relative to and/or in combination with other measures, as a tool to inform 131 clinical intervention in a given population or health care setting. To demonstrate 132 clinical utility, a separate set of studies is required3. Clinical utility studies usually 133 inform programmatic strategy and are thus the responsibility of programme 134 managers, ministries of health and other related bodies in individual WHO Member 135 States. Such studies do not fall under the scope of WHO prequalification. 136

B. How to apply these specifications. 137

For the purposes of WHO prequalification, immunoassays for the detection of 138 HBsAg shall comply with the specifications in Part 1 and Part 2 of this document. 139

Confirmatory assays using the principle of hepatitis B antigen specific antibody 140 neutralization shall comply with Parts 1-3 of this document. However, if the assay 141 is being claimed for use as a general confirmatory assay, it should be validated at a 142 regional level. More extensive clinical studies are required which are outside the 143 scope of this document. 144

C. Other guidance documents 145

This document should be read in conjunction with other relevant WHO guidance 146 documentation, including: 147

WHO prequalification documents4: 148

• Technical Guidance Series for WHO Prequalification – Diagnostic Assessment; 149

• Sample Product Dossiers for WHO Prequalification – Diagnostic Assessment; 150

• Instructions for Compilation of a Product Dossier, WHO document PQDx_018. 151

WHO Global Hepatitis programme guidelines: 152

• Guidelines for the prevention, care and treatment of persons with chronic 153 hepatitis B infection5; 154

• Guidelines on hepatitis B and C testing6; 155

• Guidelines on hepatitis B and C testing - Policy brief7. 156

3 See the International Medical Device Regulators Forum (IMDRF) document GHTF/SG5/N6:2012 Clinical Evidence

for IVD medical devices – Key Definitions and Concepts for more information:

http://www.imdrf.org/docs/ghtf/final/sg5/technical-docs/ghtf-sg5-n6-2012-clinical-evidence-ivd-medical-devices-

121102.pdf 4 These documents are available at http://www.who.int/diagnostics_laboratory/evaluations/en/ 5 https://apps.who.int/iris/bitstream/handle/10665/154590/9789241549059_eng.pdf?sequence=1 6 http://apps.who.int/iris/bitstream/handle/10665/254621/9789241549981-eng.pdf?sequence=1 7http://apps.who.int/iris/bitstream/handle/10665/251330/WHO-HIV-2016.23-eng.pdf?sequence=1&isAllowed=y



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D. Performance principles for WHO Prequalification 157

D.1 Intended use 158

An IVD intended for WHO prequalification shall be accompanied by a sufficiently 159 detailed intended use statement. This should allow an understanding of at least the 160 following. 161

• the assay type and analyte (e.g. colorimetric enzyme immunoassay for the 162 detection of HBsAg); 163

• the clinical indication and function of the IVD (e.g. for the detection of HBsAg 164 in human whole blood, serum or plasma: for screening blood donations; as an 165 aid to diagnosis of liver disease; for testing individuals at increased risk of 166 infection with HBV); 167

• the result output; 168

• the testing population for which the functions are intended (e.g. see WHO 169 Global Hepatitis programme guidelines); 170

• the intended operational setting (e.g. blood banks, hospital laboratories, 171 clinical laboratories); 172

• the intended user; 173

• the intended specimen type (e.g. plasma, serum, dried blood spots specimens 174 (DBS)); 175

• any limitations to the intended use (e.g. not validated for use on neonates). 176

D.2 Diversity of specimen types, users and testing environments and 177

impact on required studies 178

For WHO Prequalification submission, clinical performance studies shall be 179 conducted using each specimen type (e.g. serum, plasma, DBS) claimed in the 180 instructions for use (IFU). 181

Laboratory demonstration of equivalence between specimen types without 182 evidence of clinical validation is insufficient. For example, studies that comprise the 183 testing of left-over/repository specimens by research and development staff at a 184 manufacturer’s facility shall not, on their own, be considered sufficient to meet 185 many of the clinical performance study requirements summarized in this 186 document. The clinical evaluations shall demonstrate that the diagnostic specificity 187 and sensitivity are as claimed for each specimen type. 188

Immunoassays prequalified by WHO are likely to be used by laboratory 189 professionals in low- and middle-income countries in different geographical 190 settings. Depending on the intended use of an immunoassay, analytical and clinical 191 performance studies shall be designed to consider not only the diversity of 192 knowledge and skills across the population of such individuals but also the likely 193 operational settings in which testing will occur and the variability of HBV in the 194 intended population. 195

D.3 Applicability of supporting evidence to IVD under review 196

Performance studies shall be undertaken using the specific, final (locked down) 197 version of the immunoassay intended to be submitted for WHO prequalification. 198 For WHO prequalification, design lock-down is the date that final documentation 199 including quality control and quality assurance specifications is signed off and the 200 finalized method is stated in the IFU. Where this is not possible, a justification shall 201 be provided and additional supporting evidence may also be required, which might 202 occur in the case of minor variations to design where no impact on performance 203



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has been demonstrated (see WHO document PQDx_121 Reportable Changes to a 204 WHO Prequalified In Vitro Diagnostic Medical Device)8. 205

The protocol and IFU provided to laboratories for the studies outlined in Part 2 and 206 3 of this document and the final version of the IFU intended for users shall be 207 provided with the submission to WHO prequalification. If the test procedure in the 208 IFU is changed in any way after completing performance verification and validation 209 studies the change shall be reported to WHO, including a documented rationale for 210 the change, and an explanation of why the study results support the claimed 211 performance. 212

Specific information is provided in this document for the minimum numbers of lots 213 required for each study. Where more than one lot are required, each lot shall 214 comprise different production (or manufacturing, purification, etc.) runs of critical 215 reagents, representative of routine manufacture. It is a manufacturer’s 216 responsibility to ensure, via risk analysis of its IVD, that the minimum numbers of 217 lots chosen for estimating performance characteristics considers the variability in 218 performance likely to arise from the interlot diversity of critical components and 219 their formulation or from changes that could occur during the assigned shelf life of 220 the IVD. 221

Where the manufacturer supplies the instrumentation required to conduct the 222 assay, (e.g. a closed system), safety and performance data obtained using this 223 instrumentation shall be provided in the dossier. 224

Performance shall be established in comparison to a well-established device (e.g. 225 WHO prequalified, FDA-approved, CE-marked or otherwise approved by a stringent 226 conformity assessment body). Discrepant specimens should be resolved as far as 227 reasonable however performance characteristics shall be based on the original 228 result. Comparison with a similar device is insufficient for complete resolution of 229 discrepant specimens (e.g. other method from the same manufacturer or other 230 method using the same antigens provided by the same supplier). However, 231 information on the clinical state of the donor (e.g. the presence of anti-HBV core 232 IgM, measurement of viraemia, proof of quenching of the HBsAg signal by a 233 confirmatory system) may be helpful. 234

Estimation (and reporting) of IVD performance shall include the rate of invalid 235 results and the 95% confidence interval around the estimated values for key 236 performance metrics, as appropriate. Where a performance value is stated in this 237 document it is to be taken as the limit of 95% confidence of the results e.g. a 238 requirement of 90% diagnostic sensitivity implies that the lower 95% confidence 239 limit of the performance claimed will be ≥90%. 240

For certain analytical performance studies it may be acceptable to use contrived 241 specimens e.g. where normal human specimens have been spiked with those 242 containing HBsAg. Clinical studies shall be based on testing in natural specimens in 243 Part 2 and 3. 244

For IVDs that include a claim for detection of multiple analytes, evidence of 245 performance shall be provided for each claimed analyte. It should be noted that, 246 depending on the design of an IVD, evidence generated in a similar, related product 247 will usually not be considered sufficient by WHO to support performance claims in 248 an IVD submitted for prequalification. 249

8 http://apps.who.int/iris/bitstream/handle/10665/251915/WHO-EMP-RHT-PQT-2016.01-

eng.pdf;jsessionid=30D5BF0B09FFDA3B38A1698E65C8B496?sequence=1



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Example: the HBsAg performance of a combined HBsAg – HIV immunoassay 250

cannot be inferred from that of an immunoassay intended to detect HBsAg alone 251

even if the HBsAg related components are identical. 252



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E. Table of requirements 253

PART 1 ANALYTICAL PERFORMANCE AND OTHER EVIDENCE

1.1 Stability of sample(s)

1.1.1 Specimen collection, storage and transport

1.2 Validation of specimens

1.2.1 Demonstration of equivalence between specimen types

1.3 Metrological traceability of calibrator and control material values

1.3.1 Metrological traceability of values assigned to calibrator and control materials

1.4 Precision (repeatability & reproducibility)

1.4.1 Repeatability, reproducibility

1.5 Analytical sensitivity

1.5.1 Limit of detection for HBsAg

1.6 Analytical specificity

1.6.1 Potentially interfering substances

1.6.1.1 Endogenous

1.6.1.2 Exogenous

1.6.2 Cross-reactivity

1.7 High dose hook effect

1.7.1 Prozone/High dose hook effect

1.8 Validation of the assay cut-off

1.8.1 Validation of the assay cut-off

1.9 Validation of the assay procedure

1.9.1 Validation of assay parameters

1.9.2 Procedural controls

1.9.3 Sample carry over

1.10 Usability/human factors

1.10.1 Flex studies

1.11 Stability of the IVD

1.11.1 General requirements

1.11.2 Shelf-life (including transport stability)

1.11.3 In-use stability (open pack/open vial)

1.12 Performance panels

1.12.1 Genotype & serotype panels

1.12.2 Seroconversion panels

PART 2 CLINICAL EVIDENCE

2.1 Diagnostic sensitivity & specificity


2.1.2 Diagnostic sensitivity

2.1.3 Diagnostic specificity

PART 3 EVIDENCE FOR THE PERFORMANCE OF CONFIRMATORY (NEUTRALISATION) REAGENTS, IF PROVIDED

3.1 General requirements

3.1.1 Specimens

3.1.2 Users

3.2 Performance requirements 3.2.1 HBsAg reactive specimens 3.2.2 Falsely reactive specimens

254

Part 1: Analytical Performance Technical Specifications for submission to WHO Prequalification – Diagnostic Assessment: Immunoassays to detect hepatitis B surface antigen TSS 14

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Part 1: Analytical Performance and Other Evidence (non-clinical evidence) 255

Aspect Testing requirements Notes on testing requirements Source documents

1.1 Stability of sample(s)

1.1.1 Specimen collection, storage and transport

1. Real time studies shall be determined for each specimen type taking into account:

• storage conditions (duration at different temperatures, temperature limits, freeze/thaw cycles)

• specimen collection and/or transfer devices intended to be used with the IVD

• conditions and time duration before arriving in the laboratory (e.g., transport)

2. Testing in a minimum of 10 specimens tested (see notes 1 & 3)

3. Specimen panel shall include:

• 1 weak reactivity specimen (2-3 x cut-off signal)

• 1 medium reactivity specimen

• 1 strong reactivity specimen

1. Evidence shall be provided which verifies the maximum and minimum allowable times between specimen collection, processing of the specimen and its addition to the IVD.

2. Specimens of the desired reactivity may be manufactured by spiking with HBsAg positive specimens in the appropriate matrix for all claimed specimens if no genuine specimens can be obtained:

• subject to documented risk assessment

• specimens from different patients and different disease stages shall be used and documented

3. If eluate from a DBS is a claimed specimen type, the details of the filter paper (brand, product code) shall be specified and included in the IFU of the HBsAg assay and it’s use and stability validated

• allowed storage times and conditions of the specimen prior to loading on the paper, duration on the paper and of the eluate once prepared

4. In case the use of archived/stored specimens is considered for Part 1, Part 2 or Part 3 of this document, evidence of specimen stability shall be demonstrated

1.2 Validation of specimens

1.2.1 Demonstration of equivalence

1. Equivalence of specimen types shall be demonstrated

• 50 reactive specimens for each claimed specimen type

1. The relationship between IVD performance for claimed specimen types (e.g. serum and EDTA plasma) and analytical sensitivity and materials used for analytical studies shall be established. The design of subsequent

TGS-3 (1)


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of specimen types

• 50 non-reactive specimens for each claimed specimen type

2. If equivalence is claimed between different anticoagulants, testing shall be conducted in at least:

• 25 reactive specimens of each claimed anticoagulant

• 25 non-reactive specimens of each claimed anticoagulant

3. If specimens other than plasma and serum are claimed, (e.g. eluate from DBS), then agreement of results shall be demonstrated using paired specimens; (i.e. testing of a specimen of each type in each claimed matrix, see note 2)

studies shall take that relationship into account

2. If claiming equivalence between specimens derived from venous whole blood (e.g. plasma collected in different anticoagulants, serum), then paired specimens shall be used.

3. If weak reactivity clinical specimens are not available, negative individual specimens may each be spiked with the same small (less than 5% v/v) amount of a known positive specimen and the results analysed for variability within and between specimen types and between donors

• Results from the negative specimens of different specimen types should be analysed to evaluate potential differences that could imply potential false reactivity in a larger testing population

4. A third of the reactive specimens chosen should be at 2 – 3 x immunoassay cut-off and the rest across the dynamic range

European Commission decision on CTS (2)

1.3 Metrological traceability of calibrator and control material values

1.3.1 Metrological traceability of values assigned to calibrator and control materials

1. The metrological traceability to a conventional international standard shall be determined for any quantitative control(s) or calibration material provided with the IVD

1. The version of the international standard used shall be stated

2. In some jurisdictions there is a requirement for use of a ‘National Testing Panel’ for lot release and IVD validation. Such a national requirement does not remove the need for evidence of traceability to a validated reference material as described here

ISO 17511 (3)

ISO 15198 (4)

TRS 1004 Annex 6 (5)


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1.4 Precision

1.4.1 Repeatability & reproducibility

1. Precision (repeatability and reproducibility) shall be estimated using panels of at least the following spiked specimens:

• 1 non-reactive specimen

• 1 weak reactivity specimen (2-3 x assay cut-off)


2. Each panel member shall be tested:

• in 5 replicates per test

• over 5 days (not necessarily consecutive) with one run per day (alternating morning/afternoon)

• repeated in totality with 3 different lots (see note 4)

• at each of 3 different sites

3. For all precision studies, the effect of operator-to-operator variation on IVD performance should be included as part of the precision studies except for those fully automated IVDs where the effect of operator is negligible

4. Testing shall be conducted:

• by trained laboratory staff representative of intended users in addition to members of manufacturer’s staff unassisted

• using only those materials provided with the IVD (e.g. IFU, labels and other instructional materials)

1. Studies shall be statistically designed and analysed to identify and isolate the sources and extent of any variance

• within or between -run, -lot, -day, -site, -users, users-and-staff members

• any imprecision that could lead to failure to detect critical weak specimens shall be reported

2. The testing panel shall be the same for all operators, lots and sites

3. To understand irregularities in results obtained, at least 2 lots should be tested at each of the 3 testing sites

4. Each lot shall comprise different production (or manufacturing, purification, etc.) runs of critical reagents

5. The effect of operator-to-operator variation on IVD performance may also be considered as a human factor when designing robustness studies (see 1.10 Usability/human factors)

6. Operators’ profiles shall be detailed in the submission: for example, affiliation and skill level

7. Results provided shall be reported as mean, standard deviation (SD), and coefficient of variation (CV) for each specimen

8. IVDs which include eluate from DBS as a specimen type shall include evidence of precision in, at a minimum, DBS prepared from spiked whole blood specimens

CLSI EP05-A3 (6)

EN 13612 (7)

CLSI EP12-A2 (8)


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1.5 Analytical sensitivity

1.5.1 Limit of detection for HBsAg

1. The LOD of HBsAg shall be estimated (see note 1):

• for all major serotypes of HBsAg prevalent in the setting where the IVD is intended to be marketed

2. The LOD shall be traceable to international standards (see reference 3, 5) or to validated commercial secondary standards

3. Determination shall be according to an approved statistical method (see note 2)

4. Replicate testing shall be conducted on 3 different days

5. Using a minimum of 2 different lots

6. LOD shall be estimated for all specimen types

1. The LOD is defined as the lowest concentration of analyte that can be consistently detected

• Sensitivity for HBsAg shall be given with a 95% confidence interval that considers lot to lot variation.

2. For acceptable test methodologies see reference 9. For qualitative assays the logistic fit method is acceptable.

3. The version of the international standard used shall be stated.

4. If more than one type of plasma is claimed, LOD can be validated through matrix equivalency (see section 1.2.1).


ISO 17511 (3)

TRS 1004 Annex 6 (5)

CLSI EP17-A (9)

Norder, H (10)


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1.6 Analytical specificity

1.6.1

Potentially interfering substances

1. The potential for false results (false non-reactive and false reactive results) arising from interference from at least the substances/conditions listed below shall be determined using:

• a minimum of 100 specimens overall

• substances/conditions represented, by at least 5–10 specimens from different individuals

2. Testing shall be undertaken in HBsAg non-reactive and HBsAg reactive specimens (see note 1, 6); for each potentially interfering substance at high physiologically relevant levels or medically relevant dosages

3. Testing in 1 lot

1. Specimens may be spiked

2. The risk assessment conducted for an IVD shall identify substances/conditions where the potential for interference can reasonably be expected with the analyte to be detected (i.e. HBsAg) in the areas of intended use and in resource limited settings:

• by conducting and documenting appropriate risk assessment, testing can be performed on specimens spiked with the substances/conditions identified as likely to be significant and testing of potentially irrelevant substances/conditions avoided

• not simple reliance on published lists of such compounds and conditions which might be of limited relevance to this analyte

• under some circumstances stringent risk evaluation might eliminate the necessity to test some of the items in the test requirements column (see paragraphs above) but any such decision shall be documented in the submissions to WHO and considered in the risk-benefit statements

3. Effects shall be calculated for each potential interfering or cross-reacting substance separately, it is unacceptable to pool the data from different substances

4. Any effect must be evaluated against the probability of that effect occurring, given the prevalence of that substance in each of the populations intended to be tested and the clinical significance of the effect

5. Any observed interference shall be investigated and


CLSI EP07 (11)

CLSI EP37 (12)

ISO 14971 (13)

US FDA (16)

1.6.1.1

Endogenous

1. Human antibodies to the expression system e.g. human anti-mouse antibody (HAMA)

2. effects of multiple blood transfusions

3. pregnancy (including specimens from multiparous women)

4. haemoglobin, lipids, bilirubin and protein

5. elevated immunoglobulin concentrations

6. rheumatoid factor

7. sickle-cell disease

8. other autoimmune conditions including systemic lupus erythematosus (SLE) and anti-nuclear antibodies (ANA), autoimmune hepatitis

1.6.1.2

Exogenous

1. Medicines relevant to the populations intended to be tested


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• e.g. interferon, antivirals, anti-parasitic, antimalarial and anti-tuberculosis medicines

• common over-the-counter analgesic medications (e.g. aspirin, paracetamol, ibuprofen)

• biotin (see note 8)

limitations of the IVD reported in the IFU and taken into consideration in the required risk– benefit statements

6. Interference studies should be performed with HBsAg reactive specimens with a concentration near the LOD

7. The lot used in testing shall be the same lot as used in section 1.5.1 LOD studies.

8. If biotin is commonly used as a supplement and the technology of the test employs streptavidin, then biotin levels of up to 3500 ng/ml should be tested as part of this study

9. Evaluation of endogenous interfering substances may be addressed as part of the clinical studies (as applicable)

1.6.2

Cross-reactivity

1. The potential for false results arising from cross-reactivity (see note 1) shall be determined using at least 5 patient specimens of each of the following conditions/infections/diseases:

• other hepatitis viruses including hepatitis C, hepatitis A, hepatitis E

• other viral infections: measles, influenza A and B, cytomegalovirus, Epstein–Barr virus, varicella zoster virus, herpes simplex virus, HIV 1 and 2 and HTLV

• bacterial/parasitic infections including: malaria, visceral leishmaniasis, gonorrhoea, syphilis, trichomonas, human African trypanosomiasis, schistosomiasis

• other unrelated conditions known or suspected to cause cross-reactivity in HBsAg immunoassays (see note 1)

• recent vaccinations for example against: influenza, hepatitis B, yellow fever

• non-viral hepatitis

The types of conditions/diseases tested shall be risk-based, taking into consideration the operational setting as well as the intended testing population in the areas of intended use and not simply rely on published lists of such cross-reactivity which might be of limited relevance in resource limited settings

• See 1.6.1, notes 1,2,3

Any observed cross-reactivity shall be investigated, and performance limitations of the immunoassay reported in the IFU and taken into consideration in the required risk-benefit statements

For evaluation of cross-reactivity, studies should be performed using specimens with high content of the supposed interfering substance.


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1.7 High dose hook effect

1.7.1 Prozone/High dose hook effect

1. The potential for a prozone/high dose hook effect shall be determined:

• using at least 3 different lots

• using multiple, high titre specimens (minimum of 10)

• using at least 2 different concentrations of each specimen type(diluted by at least a factor of 10)

2. If a prozone is detected it shall be noted in the IFU and mitigation actions shall be described

1. High reactivity specimens should be chosen and investigated to identify the high titre specimens

2. Specimens shall be chosen that have a high analyte concentration as determined using an IVD method other than the IVD under evaluation and from a different manufacturer

• This second method shall be of a design that is not subject to prozoning

3. An increase in signal upon dilution of a specimen implies a high dose hook effect

Butch, AW (14)

TGS-6 (16)

1.8 Validation of the assay cut-off

1.8.1 Validation of assay cut-off

1. The way in which any cut-off and grey zone used in the IVD was established shall be justified

2. The validation testing should include:

• 100 reactive specimens: (weak (2-3 x cut-off signal), medium and high reactivity)

• 1000 non-reactive specimens

3. The sensitivity at the cut-off shall be determined by testing dilutions of the WHO IS which covers the signal range from above to below the cut-off

1. “Cut-off” may refer to the value used to assign reactive or non-reactive status to a result

2. The statistical methods used should be described (e.g., Receiver Operator Characteristic [ROC])

3. The testing should be repeated in different lots until the manufacturer is confident in the results

CLSI EP17 (9)

1.9 Validation of the assay procedure

1.9.1 Validation of assay parameters

1. Evidence shall be provided on how any parameters specified in the IFU (note 2) were determined, verified and validated

2. The parameters specified in the IFU commonly include the

1. These parameters may be investigated as part of 1.10 Usability/human factors studies

2. The intent of parameter validation is to demonstrate that no combination of small but defined variations in the

Montgomery, DC, (17)

IMDRF IVD MA ToC (17)


Page | 14


list below but the actual requirement is assay dependent and must be ascertained for each IVD

• timings

• volumes

• temperatures

• humidity

• speeds of addition, rotation, vibration

• washing of plates

• values assigned to control materials

• area of DBS used for elution

3. Validation of parameters shall be documented as required for each specimen type

4. Validation shall be performed using a minimum of 2 different lots (with freshly made lots of IVD and with lots towards the end of their assigned shelf lives)

5. Testing shall be with at least:


• 1 weak reactivity specimen (2 -3 x assay cut-off)


parameters of the protocol will result in the IVD failing to meet any of the manufacturer’s claims i.e. the assay is robust

3. Performance studies shall be conducted at the extremes of the intended operational temperature range; the effect of humidity on reading times shall also be investigated

4. The extent of validation shall be subject to documented risk assessment

5. Particular attention to validation shall be paid where a reading interval is specified in relation to the age of the devices to be used

6. The ranges of humidity tested shall be risk-based, taking into consideration likely operational settings in resource limited settings

PQDx_018 (19)

1.9.2 Controls

1. The IVD shall have an assay negative and positive control

2. The validity of each procedural control value shall be demonstrated

• procedural controls shall verify that the assay works as intended

1. If the control material has a defined minimum (or maximum) value it shall be demonstrated that critical specimens (e.g. specified weak reactivity specimen(s), specimen(s) with HBsAg at the claimed detection limit) will be detected as intended

2. State-of-the-art semi-automated immunoassays should have independent means of monitoring addition of specimen and other reagents

ISO 15198 (4)


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• In resource limited settings coloured reagents are an important process aid for manually loaded assays

1.9.3 Sample and reagent carry over

1. Where the manufacturer claims use of a specific instrumentation then carry over shall be evaluated on such instrumentation

2. The experiments shall investigate the individual risks identified in a risk analyses

3. Any finding shall be documented in the IFU

4. The potential impact of carry over from patient specimens shall be evaluated using high titre specimens

1. A risk analyses should assess the potential impact of carry over from patient specimens and assay reagents. Carry over should be considered if the instrumentation is used for the detection of different analytes (e.g. HIV, hepatitis C etc.)

2. High reactivity specimens should be chosen and investigated to identify the high titre specimens

1.10 Usability/human factors

1.10.1 Flex studies

1. Evidence shall be provided on how any parameters specified in the IFU were determined, verified and validated if not already addressed in 1.9.1

2. The influence of the following factors on expected results (both reactive and non-reactive) shall be considered (see note 1)

• The influence of potential user errors in method parameters and effects from the environments of intended use on IVD performance shall be evaluated:

•when reasonable excursions from IFU parameters occur (see notes 1 & 3)

•when environmental factors vary within foreseeable ranges (see note 2)

3. Robustness: any numerical factor in the IFU provided and/or identified by risk assessment (see note 3)

4. Ruggedness

1. The listed factors are not exhaustive. Refer to WHO document PQDx_018 “Instructions for compilation of a product dossier” for other flex studies that may be relevant, taking into consideration the broad range of operational and environmental conditions consistent with intended use in resource limited settings

2. The factors listed opposite should be investigated in ways that not only reflect, but also exceed, likely operating conditions in lower- and middle-income countries so that the limitations of the device can be understood

• For example, in addition to investigating deviations of temperature within those claimed in the IFU, temperature ranges should be investigated that exceed those of claimed operating conditions and which could cause test failure (incorrect/invalid results)

ISO 14971 (13)

PQDx_018 (19)

IEC 62366 (20)


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• IVD in final packaging shall be subjected to drop-shock testing

• IVD sturdiness including robustness of packaging and labelling (including evaluating for risk of leakage)

• permanence of component labels: print legibility, adhesiveness

• effects of lighting and humidity (see note 4)

• residual volumes and characteristics of liquids (potential evaporation, pH changes, microbial growth, antimicrobial efficacy of biocides)

5. Where the manufacturer provides instrumentation the following shall be considered:

• ruggedness

• impact of dust and mould on componentry (e.g. optics)

3. Each of these parameters should have been investigated formally during assay verification and validation work as described in section 1.9 Validation of the assay procedure using “designed experimentation”

4. The impacts of lighting can be multiple

• the impact of lighting on an unstable substrate, which can affect preparation, incubation and reading times and conditions

• bright light causing fading of labelling

5. Ruggedness testing should evaluate potential for leakage, for the pouches and plates to be perforated

1.11 Stability of the IVD


1. If different reagent-container sizes are used in packs with different volumes of reagent (e.g. different volumes for kits with one or five microplate), stability evidence (real time, open container, in-use) shall be obtained on all variants, even if the contents of the containers are identical (see note 1 & 2)

2. Replicate tTesting at each time point shall be undertaken using a panel consisting of:


• A sufficient number of weak reactivity specimens (after elution for DBS) at 2 -3 times assay cut-off to provide evidence that each important serotype of HBV will be detected over the assigned shelf life (see note 3)

1. The lots shall be prepared from different critical components and constituents (see Section D.3: Applicability of supporting evidence to IVD under review)

2. If the claimed specimen type is either serum or plasma, the evaluation may be conducted in either of these specimen types. However, the stability of the IVD shall also be separately established for DBS where claimed as an intended specimen type

• the stability testing panel should be composed of natural (i.e. undiluted) specimens reflecting the intended use claim

• weak reactivity natural specimens would usually be obtained from seroconversion series and commercial low titre panels but this is not usually

TGS-6 (16) ISO 23640 (21) CLSI EP25 (22) TGS-2 (23) ASTM D4169 (24)


Page | 17


• any available falsely reactive specimens to ensure that the signal does not increase over the assigned shelf life (see note 5)

3. In addition, to address specificity a minimum of 100 random non-reactive specimens shall be tested at T0 and at the end of the claimed shelf life (see note 5)

4. Biocidal agents and desiccants (if applicable) shall be validated according to TGS-2

possible with coverage of the range of serotypes required so dilution is permissible

3. When more than 1 monoclonal antibody is required (or used) to show complete detection of all claimed serotypes, the testing panel shall contain at least one specimen of each claimed serotype to monitor each monoclonal separately during stability evaluation

4. The numbers of invalid results and repeat testing with each lot shall be reported

5. Appropriate risk and statistical analyses will be performed to investigate trends in background reactivity and false reactivity rates

6. Change in apparent signal (mean or variance) or an increased skewness towards the cut-off value for the random negative specimens might signal potential specificity problems if larger numbers of specimens were tested and indicate an undesirable change in stability in the IVD

7. Claims for stability shall be less than the last successful data point from the least stable lot, with, if lots are different, a statistical analysis showing that all future lots will be expected to meet the claimed life

1.11.2

Shelf life (including transport stability)

1. Testing of a minimum of 3 lots of product manufactured to:

• the final locked down design

• in the final primary packaging

• to validated manufacturing scale

• released to the final quality assurance specifications

2. The lots shall be transport stressed (simulated) before real

1. Determination of shipping stability shall be performed using simulated extreme stress conditions, ensuring that the application of those conditions is consistent and controlled

• simulation shall take into consideration the extremes of conditions likely to be encountered during shipment to intended users


Page | 18


time studies are undertaken (see note 1)

• with cyclic temperature variation (note 1)

3. IVD in final packaging shall be subjected to drop-shock testing

4. Stability of labelling shall be determined (see note 2)

• simple transport is insufficient to simulate all conditions that an IVD might encounter during shipment to a variety of resource limited settings in a variety of seasons

2. Stability of labelling shall be determined under the conditions of intended and expected use

• In addition to routine transport stress (shock testing of defined types) the resilience of labels (e.g. strength of attachment, print stability, legibility over time, humidity) shall be evaluated as part of shelf-life verification

1.11.3 In-use stability (open pack/open vial)

1. Testing of a minimum of 1 lot as follows:

a. the final locked down design b. in the final primary packaging c. to validated manufacturing scale d. released to the final quality assurance

specifications

2. There shall be evidence that once the IVD is removed from its primary packaging, it is stable across the expected temperature and humidity ranges for a defined period of time at both the beginning and end of its assigned shelf life

3. Liquid components and plates, once opened, shall have a validated life and number of stated uses under environmental (including microbial) conditions expected

1. In-use stability studies cover short-term effects (e.g. after taking a microplate out of its packaging), medium term effects (e.g. times between adding specimens and reagents to microwells before beginning the next stage of the method) and long-term effects (e.g. open pack stability on-board instrumentation, open bottle with repeated removal of aliquots over time by hand, storage of plate after opening pouch)

2. Statistically designed experiments should be designed to allow evaluation of any interactions between environmental conditions

3. Most aspects of in-use stability may be considered as part of Section 1.10 Usability/human factors

1.12 Performance panels

1.12.1 Genotype & serotype panels

1. The IVD should be shown to detect the major serotypes to be found in the regions of intended use, at a minimum:

1. Testing should be performed using a minimum of 2 different lots as defined in Section D3 (D.3 Applicability of supporting evidence to IVD under review)



Page | 19


• adr, adw, ayw with every effort being made to test ayr if marketing is expected in endemic regions

• genotypes are only loosely related to serotypes, and monoclonal antibodies used in HBsAg assays can be serotype specific but are very rarely genotype specific

• genotype panels are frequently also serotyped e.g. 1st WHO International Reference Panel for HBV Genotypes for HBsAg assays

2. The IFU shall clearly state if mutant panels have not be evaluated on the IVD

Ribas-Aparicio, RM (25)

Brunetto MR (26)

1.12.2 Seroconversion panels

1. A minimum of 20 commercial or well characterized HBsAg seroconversion panels shall be tested which:

• individually start with bleeds negative for the HBsAg and have narrow bleeding date intervals

• some of the panels must be over sufficient time to allow antibody seroconversion to have occurred, e.g. to IgM anti-core but ideally to IgG anti-HBsAg (see note 2)

2. Seroconversion specimens shall be detected in equivalence to a state-of-the-art assay based as indicated by the seroconversion series supplier’s data sheets and current peer reviewed scientific literature

3. Testing shall be conducted using a minimum of 1 lot

1. Panels should have been collected at short intervals to cover the seroconversion period

2. There are reported cases of infection from anti-HBsAg positive specimens which obscured detection of the presence of HBsAg by some assays

• state of the art assays should detect HBsAg in the presence of anti-HBsAg

256

Part 2: Clinical Evidence Technical Specifications for submission to WHO Prequalification – Diagnostic Assessment: Immunoassays to detect hepatitis B surface antigen TSS 14

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Part 2: Clinical Evidence 257


2.1 Diagnostic sensitivity and specificity

2.1.1 General requirements for sensitivity and specificity studies

1. Diagnostic sensitivity and specificity shall be determined:

• in specimens from different geographical settings (minimum of 2 regions) with different serotypes represented at each

• by laboratories representative of different intended use settings (e.g. primary, secondary and tertiary laboratory settings) (see note 1)

• using at least 2 different lots in each laboratory (see note 2)

1. Prequalified HBsAg immunoassays are generally used by trained laboratory staff in resource limited settings. This should be considered when preparing evaluation protocols

2. Lots used for clinical evaluation studies shall comprise different batches of critical components (as described in Section D.3

3. Results shall be expressed separately for each specimen type and for each specimen type per intended use (no aggregation of results)

4. If the claimed specimen types are serum and plasma, the evaluation may be conducted in either of these specimen types. However, the clinical performance shall be established in DBS where considered as an intended specimen type, and sufficient numbers of each specimen type shall be tested so that the claimed sensitivity and specificity is met

5. Specimens for testing may include:

• Freshly taken, unfrozen routine specimens stored as in the IFU

• Appropriately stored, well characterized sera that have not undergone more than one freeze-thaw cycle may also be used for clinical evaluation testing if necessary assuming that freezing specimens has been validated during analytical studies (see

TGS-3 (1)

CLSI EP12-A2 (8)

WHO (27)



Page | 21


paragraph 1.1.1, note 4). These shall be a random selection of consecutively chosen specimens

6. The protocol should specify the criteria for unbiased patient selection with associated risk analysis but in general there should be no exclusions except for ethical reasons

7. The patients should be classified, and results analysed accordingly (e.g. first time or repeat blood donors, concomitant infections, age, gender, medications taken including antivirals, recent vaccinations)

8. Samples for both comparator assay and the IVD under evaluation shall be taken from the same specimen container

9. Performance characteristics shall be reported using initial results, only. The results of further testing of specimens with discrepant results shall be reported separately as additional information about IVD performance

10. Problematic specimens including those with unexpected results, but which otherwise meet selection criteria for a study, shall not be systematically excluded from analysis

• Indeterminate results shall not be systematically excluded from the denominator data for analysis

11. All invalid results shall be recorded

12. Estimates of diagnostic/clinical sensitivity and specificity shall be reported with 95% confidence intervals


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2.1.2 Diagnostic sensitivity

1. Testing of a total of at least 400 specimens confirmed as HBsAg positive from at least two different geographical regions (see notes 1)

2. Discrepant and unexpected results shall be fully evaluated (see notes 3-8)

1. At least 50% of the results from which the diagnostic sensitivity is calculated shall be from fresh specimens taken from routine sequential sampling

2. The comparator method shall be a state of the art HBsAg assay which is not from the same manufacturer as the IVD under evaluation

3. All initially reactive specimens on the comparator or IVD under evaluation or both shall be subjected to full characterization of the HBsAg status using a pre-determined algorithm

• the algorithm shall include two state of the art immunoassays including the comparator assay

• at least one of the assay results shall be verified with a confirmatory quenching assay

• note that simple agreement with a single laboratory result (e.g. just the comparator) is insufficient to characterize reactive specimens for clinical evaluation studies – potential for common false reactive results.

4. The algorithm for testing and assigning status shall be determined and documented before the commencement of testing and based on the comparator and reference IVDs available to the studies

5. Rapid diagnostic tests shall not be used as the comparator test nor be part of the testing algorithm

6. Specimens reactive in the comparator IVD, negative in the IVD under evaluation but confirmed positive shall be tested in all available lots of the IVD and reported in the dossier:


Page | 23


• i.e. those initially false negative on the IVD under evaluation

7. Assessment shall be made of the potential for false reactive results in common between the comparator IVD and the IVD under evaluation

8. Reactive specimens on the IVD under evaluation that are confirmed negative shall be tested in all available lots of the IVD and reported in the dossier

• i.e. initially false reactive on both test and comparator IVD, common false reactive results

2.1.3 Diagnostic specificity

1. Testing of sufficient confirmed non-reactive specimens to provide evidence of specificity suitable for the intended use (see notes 1 & 3)

2. Typically for blood donor screening at least 5000 specimens and for testing hospitalised patients at least 200 specimens should be tested (reference 2)

• The required numbers may be significantly higher to tighten the statistical range of claimed performance (see section D3)

1. At least 80% of the results from which the diagnostic specificity is calculated shall be from fresh specimens

2. Discrepant results shall be evaluated as for those found in the studies for section 2.1.2

3. Specificity might differ depending on the claimed use, for example blood donation versus clinical laboratories

• The recommended specificity for blood donation screening is usually higher than for clinical evaluation, and should be at least 99.5% (refer to WHO Screening Donated Blood for Transfusion Transmissible Infections reference 27)

4. If the intended use covers both blood screening and clinical screening use, data should be obtained from both blood screening and clinical screening laboratories


WHO (27)

258

Part 3: Confirmatory (neutralisation) reagents Technical Specifications for submission to WHO Prequalification – Diagnostic Assessment: Immunoassays to detect hepatitis B surface antigen TSS 14

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Part 3: Evidence for performance of confirmatory (neutralisation) reagents, if provided 259

260


3.1 General requirements

3.1.1

Specimens

1. Evidence shall be provided of neutralisation of HBsAg reactive specimens for the specimen types validated in paragraph 1.2.1 above (see note 1)

2. Evidence shall be provided of specimen stability prior to neutralisation (see note 2)

3. Evidence shall be provided that false reactive specimens are not neutralised (see note 3)

1. The HBsAg reactive specimens should be confirmed as in section 2.1.2 of this document

2. Specimen stability should be demonstrated which allows time for the specimens to be evaluated as necessary prior to confirmation

3. False reactive specimens should be collected for this purpose throughout product development in addition to during the clinical evaluations


3.1.2 Users

1. The intended users of the confirmatory reagents shall be the same as those of the predicate device

• users of the same expertise, training and in the same geographical settings as in part 2 of this document

• ideally the confirmatory reagents should be evaluated along with the predicate device

3.2 Performance requirements

3.2.1 HBsAg reactive specimens

1. All reactive HBsAg specimens that are tested shall be confirmed by the confirmatory (neutralisation) reagents (note 1)

2. HBsAg reactive specimens of as many serotypes as possible should be evaluated including at least adw, adr, ayw and ayr (note 2)

3. HBsAg reactive specimens shall be from at least 2 geographical regions

1. Very weak reactivity specimens might fail to satisfy the criteria for confirmation. If so, the IFU shall contain a warning addressing this

2. HBsAg reactive specimens may be sourced commercially, sourced from laboratory archives or found during clinical evaluation. All specimens shall be confirmed according to section 2.1.2 (in part 2) of this document and the proof of their positive status documented

Part 3: Confirmatory (neutralisation) reagents Technical Specifications for submission to WHO Prequalification – Diagnostic Assessment: Immunoassays to detect hepatitis B surface antigen TSS 14

Page | 25


• Including all reactive specimens evaluated as part of the diagnostic sensitivity study in part 2 of this document

4. Specimens from patients of acute, resolving and chronic status shall be evaluated (notes 3 and 4)

• 20 specimens near the cut-off

• 20 specimens high reactivity

• At least 5 seroconversion series shall be evaluated including both ad and ay serotypes (note 4)

5. At least 10 mutant forms of HBsAg shall be evaluated

3. The high titre specimens as used to evaluate the prozone effect (section 1.7 High dose hook effect above) shall be tested with the confirmatory reagents

• high titre specimens frequently require dilution prior to neutralisation: a method and diluent for this shall be specified in the IFU

4. The whole series, after seroconversion, should be neutralised

3.2.2

Falsely reactive specimens

1. All falsely reactive specimens found during product development and during analytical and clinical evaluations shall be evaluated (note 1)

2. Falsely reactive specimens from other HBsAg assays, when available shall be tested

1. The European Common Technical Specifications (reference 2) expects that 10 falsely reactive specimens are tested

2. Some specimens might be neutralised on both the test and the control reagents

• there are several reasons why this might occur, and each might mask an underlying true positive: this should be addressed in the IFU


261


Immunoassays to detect the surface antigen of HBV

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F. Source documents 262

1. Technical Guidance Series for WHO Prequalification – Diagnostic Assessment. Principles for 263

Performance studies, TGS–3. Geneva: World Health Organization; 2016 264

http://apps.who.int/iris/bitstream/10665/258985/1/WHO-EMP-RHT-PQT-TGS3-2017.03-265

eng.pdf?ua=1 266

2. 2009/886/EC: Commission Decision of 27 November 2009 amending Decision 2002/364/EC 267

on common technical specifications for in vitro diagnostic medical devices (notified under 268

document C(2009) 9464) (Text with EEA relevance), https://eur-lex.europa.eu/legal-269

content/en/TXT/?uri=CELEX:32009D0886; 270

3. ISO 17511:2003 In vitro diagnostic medical devices -- Measurement of quantities in 271

biological samples -- Metrological traceability of values assigned to calibrators and control 272

materials. Geneva: International Organization for Standardization; 2003 273

4. ISO 15198:2004 Clinical laboratory medicine -- In vitro diagnostic medical devices -- 274

Validation of user quality control procedures by the manufacturer. Geneva: International 275

Organization for Standardization; 2004 276

5. WHO Technical Report Series, No. 1004, 2017. Annex 6. WHO manual for the preparation of 277

secondary reference materials for in vitro diagnostic assays designed for infectious disease 278

nucleic acid or antigen detection: calibration to WHO International Standards. Geneva, 279

World Health Organization; 2016 280

6. Evaluation of Precision of Quantitative Measurement Procedures; Approved Guideline - 281

Third Edition. CLSI EP05-A3. Wayne, PA: Clinical and Laboratory Standards Institute; 2014 282

7. EN 13612:2002. Performance evaluation of in vitro diagnostic medical devices. Brussels: 283

European Committee for Standardization; 2002 284

8. User Protocol for Evaluation of Qualitative Test Performance; Approved Guideline – Second 285

Edition. CLSI EP12-A2. Wayne, PA: Clinical and Laboratory Standards Institute; 2008 286

9. Evaluation of Detection Capability for Clinical Laboratory Measurement Procedures 287

Approved Guideline – Second Edition. CLSI EP17-A2. Wayne, PA: Clinical and Laboratory 288

Standards Institute; 2012 289

10. Norder, H, Couroucé, A-M and Magnius, LO, Molecular basis of hepatitis B virus serotype 290

variations within the four major subtypes, J. Gen. Virol. 73 (1992) 3141-3145 291

11. Interference Testing in Clinical Chemistry. Approved Guideline - Second Edition. CLSI EP07-292

A3. Wayne, PA: Clinical and Laboratory Standards Institute; 2018 293

12. Supplemental Tables for Interference Testing in Clinical Chemistry, 1st Edition. CLSI EP37. 294

Wayne, PA: Clinical and Laboratory Standards Institute; 2018 295

13. ISO 14971:2007 Medical devices -- Application of risk management to medical devices. 296

Geneva: International Organization for Standardization; 2007 297

14. US FDA Testing for Biotin Interference in In Vitro Diagnostic Devices Draft Guidance for 298

Industry. June 2019 299

15. Butch AW. Dilution protocols for detection of hook effects/prozone phenomenon. Clin 300

Chem. 2000; 46:1719-21 301

16. Technical Guidance Series for WHO Prequalification – Panels for quality assurance and 302

quality control of in vitro diagnostic medical devices. Geneva: World Health Organization; 303

http://apps.who.int/iris/bitstream/10665/258985/1/WHO-EMP-RHT-PQT-TGS3-2017.03-eng.pdf?ua=1

http://apps.who.int/iris/bitstream/10665/258985/1/WHO-EMP-RHT-PQT-TGS3-2017.03-eng.pdf?ua=1

https://eur-lex.europa.eu/legal-content/en/TXT/?uri=CELEX:32009D0886

https://eur-lex.europa.eu/legal-content/en/TXT/?uri=CELEX:32009D0886


Immunoassays to detect the surface antigen of HBV

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2017 http://apps.who.int/iris/bitstream/handle/10665/259408/WHO-EMP-RHT-PQT-304

2017.10-eng.pdf;jsessionid=1453181F82348045800D6E6C06AEDEF1?sequence=1 305

17. Montgomery, D.C., Design and Analysis of Experiments, 8th edn. ISBN 978-1-118-09793-9, 306

John Wiley, 2012 307

18. In Vitro Diagnostic Medical Device Market Authorization Table of Contents (IVD MA ToC). 308

IMDRF/RPS WG/N13(Edition 2) FINAL:2019. IMDRF 2019. 309

http://www.imdrf.org/docs/imdrf/final/technical/imdrf-tech-190321-ivd-mdma-toc-n13.pdf 310

19. WHO Prequalification – Diagnostic Assessment: Instructions for Compilation of a Product 311

Dossier. WHO PQDx_018 v3, 27 August 2014. Geneva: World Health Organization; 2014 312

(http://www.who.int/entity/diagnostics_laboratory/evaluations/141015_pqdx_018_dossier313

_instructions_v4.pdf?ua=1 314

20. IEC 62366-1:2015. Medical devices -- Part 1: Application of usability engineering to medical 315

devices. Geneva: International Organization for Standardization; 2015 316

21. ISO 23640:2011. In vitro diagnostic medical devices - Evaluation of stability of in vitro 317

diagnostic reagents. Geneva: International Organization for Standardization; 2011 318

22. Evaluation of Stability of In Vitro Diagnostic Reagents; Approved Guideline. CLSI EP25-A. 319

Wayne, PA: Clinical and Laboratory Standards Institute; 2009 320

23. Technical Guidance Series for WHO Prequalification – Diagnostic Assessment. Establishing 321

stability of an in vitro diagnostic for WHO Prequalification, TGS–2. Geneva: World Health 322

Organization; 2016 http://apps.who.int/iris/bitstream/10665/259742/1/WHO-BS-323

2017.2304-eng.pdf?ua=1/ 324

24. Standard Practice for Performance Testing of Shipping Containers and Systems. ASTM 325

D4169-14. West Conshohocken, PA: ASTM International; 2014 326

25. Ribas-Aparicio, RM, Valdez-Salazar, H-A, Aparicio-Ozores, G, and Ruiz-Tachiquín, M-E, 327

Serotypes and genotypes of the hepatitis B virus in Latin America, Annual Research & Review 328

in Biology 4 (2014) 1307-1318 329

26. Brunetto MR, Chance and necessity of simultaneous HBsAg and anti-HBs detection in the 330

serum of chronic HBsAg carriers, J. Hepatol. 60 (2014) 473-475 331

27. Screening donated blood for transfusion transmissible infections: Recommendations. 332

Geneva, WHO 2009 333

http://apps.who.int/iris/bitstream/handle/10665/259408/WHO-EMP-RHT-PQT-2017.10-eng.pdf;jsessionid=1453181F82348045800D6E6C06AEDEF1?sequence=1

http://apps.who.int/iris/bitstream/handle/10665/259408/WHO-EMP-RHT-PQT-2017.10-eng.pdf;jsessionid=1453181F82348045800D6E6C06AEDEF1?sequence=1

http://www.imdrf.org/docs/imdrf/final/technical/imdrf-tech-190321-ivd-mdma-toc-n13.pdf

http://www.who.int/entity/diagnostics_laboratory/evaluations/141015_pqdx_018_dossier_instructions_v4.pdf?ua=1

http://www.who.int/entity/diagnostics_laboratory/evaluations/141015_pqdx_018_dossier_instructions_v4.pdf?ua=1

http://www.who.int/diagnostics_laboratory/guidance/technical_guidance_series/en/

http://www.who.int/diagnostics_laboratory/guidance/technical_guidance_series/en/

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