Requirements for serological antibody tests submitted under the COVID-19 Interim Order: guidance

Note: As research evolves and we learn more about the virus, the disease and the immune response, the requirements in this Guidance may be updated accordingly based on available scientific evidence.

Date posted: 2020-04-24
Last updated: 2020-04-28

Table of contents

Background

The purpose of this document is to provide guidance to manufacturers of serological assays intended for the detection of antibodies to SARS-CoV-2, the virus that causes COVID-19 disease. The guidance outlines recommendations regarding the minimum testing that should be performed for SARS-CoV-2 diagnostics to support an application for an authorization under the Interim Order Respecting the Importation and Sale of Medical Devices for Use in Relation to COVID-19.

The Minister of Health approved the Interim Order on March 18, 2020, which is one of the fastest mechanisms available to address large-scale public health emergencies. Health Canada reviews all COVID-19-related submissions and applications as quickly as possible without compromising patient safety.

Under the Interim Order, manufacturers are required to submit an abbreviated application to support the safety, effectiveness and quality of their medical device. There are no fees associated with an application through the Interim Order pathway. As well, manufacturers applying through this pathway do not have to hold a Medical Device Single Audit Program (MDSAP) certification. This is the most effective pathway manufacturers can follow in order to apply for authorization.

Health Canada has developed a guidance document to support applications submitted under the Interim Order, which should be read in conjunction with this document.

Quality, safety and effectiveness information

4(1)(g) of the Interim Order requests that the applicant provide the known information in relation to the quality, safety and effectiveness of the device.

Quality management system

For quality management system requirements, refer to the guidance document Applications for medical devices under the Interim Order for use in relation to COVID-19

Attestation for post-market oversight

Section 4(1)(i) of the Interim Order requests the submission of an attestation supporting that documented procedures are in place in respect of distribution records, complaint handling, incident reporting and recalls.

Manufacturing, ramping up capacity and estimates of distribution to Canada

Provide information on the manufacturing capacity and the allocation process, including estimates of distribution to Canada.

Lot release program

Provide a description of the lot release program in place to ensure that each production lot meets the established specifications. The information required includes a detailed protocol, a description of the testing panel, and a description of the acceptance criteria.

Conformance to standards

If the serological test requires use of an instrument, a declaration of conformance to standards is required. For further information, refer to the guidance on recognition and use of standards.

Intended use

The proposed intended use will be finalized based on the supporting data for the specific intended use of the device, and on recommendations from Public Health authorities at the time of authorization. Recommended text is provided below as an example of key elements that should be included in the intended use statement for serological tests developed to detect antibodies to SARS-CoV-2:

[Test Name] is [specify test technology] intended for the detection and/or differentiation of [antibodies (IgM and/or IgG) to SARS-CoV-2] in [describe all the specimen types] from [Describe the targeted population].

The [test name] is intended for use by [include intended user, e.g., trained laboratory personnel, healthcare professionals]. For laboratory use only (AND/OR) for Point of Care testing.

Include statements that expand on the utility and limitations of the results of the test.

Proposed indications will be considered based on the clinical information provided in the application.

Limitations related to the intended use of serological tests

Based on the information available at the present time, Health Canada will not authorize serological tests intended to be used for diagnosis or for self-testing. As research evolves and we learn more about the virus, the disease and the immune response, the requirements in this Guidance may be updated accordingly based on available scientific evidence.

The following statements should be included as limitations of serological tests:

  • This assay is not intended to be used for screening patients or as an aid for diagnosis of patients with suspected COVID-19 infection.
  • This assay is not intended for home testing (or self-testing).
  • Negative results do not preclude SARS-CoV-2 infection and should not be used as the sole basis for patient management decisions.
  • Negative results must be combined with clinical observations, patient history, and epidemiological information.
  • False negative results can occur in elderly and immunocompromised patients.
  • False positive results for IgM and IgG antibodies may occur due to cross-reactivity from pre-existing antibodies or other possible causes.

Device description

The detailed description of the assay shall include the following information:

Performance characteristics

The following section describes the validation studies expected to be submitted, where applicable, to support the performance of the test for its intended use. A detailed summary for each study, including discussion and conclusions should be provided.

Detailed Summary

The summary of the validation study should include sufficient information to allow assessment. Health Canada recommends using the proposed format outlined in Annex 1.

Unless otherwise indicated, for tests that use capillary blood as a sample type, all performance characteristics (i.e. all items identified in Section 6 of this guidance) should be validated with capillary blood specimens obtained using the specimen collection method recommended in the instructions for use.

Analytical sensitivity

Provide detailed summaries of available studies supporting the limit of detection (LoD) of the test. For ELISA, relative analytical sensitivity should be assessed by end-point dilution analysis indicating the dilution of serum in which antibodies are no longer detected. Information in the clinical study (see clinical evaluation section) will provide additional required information to demonstrate sensitivity performance.

Provide a detailed description of the analytical sensitivity study. The description should include the description of the material tested (antigen/antibody source, reference sera, etc.) and methodology used.

Cutoff

For tests using an instrument reader, provide a detailed summary of the cutoff validation study supporting the claimed cutoff concentration and/or signal detection.

Hook effect

The hook effect is observed in sandwich immunoassays, where at very high concentrations of the analyte, the assay signal is saturated. This occurs due to the elevated number of analyte molecules that bind to both the capture and detection antibody, which prevent them from forming the sandwich complexes, and therefore the signal that is detected. In practice, the signal response may decrease at extremely high concentrations, which leads to a misleading lower analyte concentration.Footnote 1

For applicable sandwich immunoassays, three to five neat or spiked specimens above the dynamic range of the assay should tested. The highest test concentration without a hook effect should be specified in the labelling.

Sample matrix

If multiple sample types are intended for clinical testing, the performance characteristics of the test should be established for each claimed sample type. Alternatively, a sample matrix equivalency study should be performed.

The sample matrix equivalency studies should provide evidence supporting the following:

If equivalency is demonstrated between two or more sample types other than capillary samples, a representative specimen type from this group may be used for the remaining analytical studies.

Cross-reactivity

Cross-reactivity studies are performed to demonstrate that the test does not react with antibodies produced against related pathogens, high prevalence disease agents, and normal or pathogenic flora that are reasonably likely to be encountered in the clinical specimen.

Evaluation of cross-reactivity to organisms listed in the List of mandatory organisms to be tested for cross-reactivity is required to be completed prior to submission. Cross-reactivity to organisms listed in Table 2 are optional and may be requested as a post-market commitment under the Interim Order.

Every effort should be made to assess cross-reactivity using a minimum of 5 pre-pandemic samples positive for IgM and for IgG antibodies directed against the pathogens listed below.

Consult with Health Canada if there is a challenge to obtain samples with these cross-reactive antibodies.

List of mandatory organisms to be tested for cross-reactivity for which cross reacting antibodies should be tested

List of optional organisms to be tested for cross-reactivity for which cross-reactive antibodies should be tested (may be a post-market condition)

Interference

Potential interferents may originate from the following endogenous and exogenous sources. Substances likely to be present in patient specimens should be tested using both negative and low positive specimens in triplicate. The concentration of the interferent intended to be measured should be clearly defined, following, as applicable, the concentrations recommended in the Clinical Laboratory Standards Institute Guidance, CLSI EP-07-A2.

Interference studies for tests intended to be used with capillary blood can performed with venous whole blood in lieu of capillary blood.

Endogenous substances

Exogenous substances

Class specificity (for antibody tests only)

Potential cross-reactivity between classes of antibody should be assessed. For IgM assays, a high level of SARS-CoV-2 IgG should be tested to determine specificity. For IgG assays, a high level of SARS-CoV-2 IgM should be tested to determine specificity.

Precision

Evidence of repeatability should be provided. If unavailable at time of submission, reproducibility studies will be requested as a condition to authorization.

Seroconversion

Every effort should be made to test seroconversion panels for antibody tests. If available, provide a complete test report including details on the seroconversion panels such as:

It is expected that commercial seroconversion panels will be available in the near future. If unavailable at time of submission, seroconversion studies will be requested as a condition to authorization.

Robustness studies

Robustness studies should be designed to challenge the system under conditions of stress. These studies identify potential device deficiencies, including failures, when subjecting the device to small but deliberate variations in conditions of use and test procedures that may occur during the normal use of the device.

The influence of the following factors on expected results (both positive and negative) must be considered when designing validation studies:

If capillary whole blood is claimed, the robustness studies need to be conducted using this specimen type and using any equipment (e.g. droppers, plastic pipettes) that come with the assay.

Stability

Provide all evidence currently available supporting the stability of the device (shelf life, in-use, shipping). Alternatively, submit a plan for these real-time stability studies that includes a proposed timeline for the stability studies. Health Canada expects that stability studies will be initiated upon authorization.

Clinical evaluation

A minimum of 50 positive samples for each immunoglobulin detected (IgG and/or IgM) and 200 negative samples by Reverse Transcription Polymerase Chain Reaction RT-PCR) from symptomatic patients should be tested.

For a test that uses an ELISA method, a reference range study should be performed with a minimum of 500 samples from the general population (preferably with respiratory symptoms) collected before November 2019.

The positive sample set should include relevant samples from the following targeted population to support the claimed intended use:

Include patient demographic information, since the group tested should include an adequate representation of different demographic subgroups, such as sex and age.

Comparator assays

Comparator RT-PCR assays should be authorized under the Interim Order. In the absence of Health Canada authorization, Emergency Use Authorization from the United States Food and Drug Administration, or declaration of eligibility for procurement by the World Health Organization under the Emergency Use Listing Procedure, will be accepted.

Verify the associated links to determine if the comparator RT-PCR assay is elegible for use as a comparison for the clinical study:

Health Canada COVID-19 Authorization

Emergency Use Authorization from the United States Food and Drug Administration

World Health Organization under the Emergency Use Listing Procedure

Results Analysis

Clinical evaluation data should be presented by time of the onset of symptoms and illness severity (e.g. severe and mild symptoms, no clinical symptoms).

Results should be analysed against acceptable comparator methods using adequate statistical analysis. Positive Percent Agreement [PPA], Negative Percent Agreement [NPA] and clinical confirmation using 95% Confidence Intervals should be provided. Further guidance on acceptable values for PPA and NPA is provided in the notice on sensitivity and specificity values for COVID-19 serological testing devices.

Point of care studies

For tests intended to be used at the Point of Care, a near patient study performed in the intended use setting and by the intended users is required. The study should be carried out by a minimum of 9 operators, under the intended conditions of use, and include a questionnaire to assess:

A point of care study is required for all tests intended to be used with capillary blood/fingerstick blood samples.

Labelling

4(1) (j) of the Interim Order requires that the applicant provide a copy of the label of the COVID-19 medical device. This label should be expressed in a legible, permanent and prominent manner, in terms that are easily understood by the intended user. Additionally, where a package that contains a COVID-19 medical device is too small to display all the information required according to section 10 of the Interim Order, the directions for use shall accompany the device but need not be on the outside of the package or be visible under normal conditions for sale.

IFU / Package Insert (PI) and reagent labels should be submitted.

A picture of each of the assay components and packaging should also be submitted, as well as any promotional material or leaflets for the device.

Where applicable, the following limitation statements should be included in the IFU. These limitations are separate, and in addition to, the limitations that are identified in the intended use statement.

Limitations

The following statements should be included as limitations of serological tests:

  • Use in conjunction with the testing strategy outlined by public health authorities in your area.
  • Negative results do not preclude SARS-CoV-2 infection and should not be used as the sole basis for patient management decisions. IgM antibodies may not be detected in the first few days of infection; the sensitivity of the test early after infection is unknown.
  • Results are for the detection of SARS-CoV-2 antibodies. IgM antibodies to SARS-CoV-2 are generally detectable in blood several days after initial infection, although levels over the course of infection are not well characterized. IgG antibodies to SARS-CoV-2 become detectable later following infection. At this time, it is unknown how long IgM or IgG antibodies may persist following infection.
  • Positive results for both IgG and IgM could occur after infection and can be indicative of acute or recent infection [and successful immune response to a vaccine, once developed].
  • False positive results for IgM and IgG antibodies may occur due to cross-reactivity from pre-existing antibodies or other possible causes.
  • The presence of specific antibodies are a sign of previous or current infection, and can also be used to determine the efficacy of treatment.
  • Laboratories are required to report all positive results to the appropriate public health authorities.
  • Test-specific limitations, as required

Post-market Authorization Condition

As we learn more about the virus, the disease, and the immune response, the requirements in this Guidance may be updated accordingly based on available scientific evidence. In consideration of the current lack of evidence, the following post-market authorization conditions will be imposed so that the utility of the tests, and the ability of the tests to perform as intended, can be assessed:

Within one month, submit a plan to Health Canada that will assess the performance of the device when used in the intended sites. The plan should include:

Collection of the clinical data should begin at Canadian sites within two weeks after Health Canada reviews the plan to assess clinical performance.

An investigational testing authorization for these post-market activities is not required. Manufacturers may show the condition of authorization to the site as a demonstration that Health Canada is aware of the study.

Annex 1 - Recommended Format for Summary of Validation Studies

  1. Study Title
  2. Objectives
    • Provide a short description of the objective of the study
  3. Methodology
    • Sample type: Description of the sample type
    • Number of samples tested (positive and negative)
    • Sample characterization: Name of the assay or method used to characterize the samples, including a description of the measure and (SARS-CoV-2 isolate or antigen source used to validate the assay)
    • Testing algorithm: Testing time-point, replicates, run, days, site, lots, etc.
    • Acceptance criteria
  4. Results
    • Tabular format is preferred whenever possible
    • Statistical analysis
    • Discrepant results (explanation and resolution)
    • Results for each setting and/or sample type
    • If available, provide results by age, sex, ethnicity
  5. Discussion and Conclusions
    • Concise discussion of the design of the study; population selected; rationale for reference or non-reference methods used; if applicable, rationale for method deviations, etc.
    • Clear conclusion supporting the performance claims made

Footnotes

Footnote 1

Sandeep K. Vashist, John H.T. Luong, in Handbook of Immunoassay Technologies, 2018

Return to footnote 1 referrer

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