SARS-CoV-2 Antibody EQA Programme

Purpose:
SARS-CoV-2 is a novel coronavirus that causes the respiratory disease COVID-19. An antibody response to infection usually occurs at around 7 days (IgM) with IgG response at around day 10-14. A number of SARS-CoV-2 antibody tests are now available for use both as a Laboratory or Point of care test. These tests are used to determine the incidence of SARS-CoV-2 infection and the prevalence of immunity in the general population. More recently they have also been used to assess the durability of antibody response post vaccination and as part of the management of immunocompromised patients.

There are several types of immunoassays available, using different viral antigens for antibody detection, such as the spike, membrane, envelope and nucleocapsid proteins. The most common antigens used are the spike protein, which contains the domain for attachment to the host cells, and the nucleocapsid protein, involved in viral replication, transcription and assembly.

These methods offer either IgG alone or total antibody and provide either qualitative or quantitative results.

Scope:
Three liquid human serum samples are distributed monthly, with a minimum of 36 samples distributed over the year covering a wide clinically relevant range. The samples consist of endogenous samples from healthy individuals collected pre-December 2019, donors previously exposed to the SARS-CoV-2 virus, convalescence plasma donations or from donors vaccinated against COVID-19. The samples are aliquoted and frozen at -20°C and where possible distributed on more than one occasion over the year. The programme allows for the assessment of the organisation’s and method’s performance, including bias, within and between batch imprecision. Data is peer reviewed separately for both Anti S and Anti N methods for both qualitative and quantitative methods with an overall interpretation based on the subjects’ clinical and vaccination status.

The samples are suitable for all routine immunoassay analysers, ELISA methods and lateral flow devices.

Key Features:

Endogenous serum from donors previously exposed to the SARS-CoV-2 virus, convalescence plasma donations or from donors vaccinated against COVID-19.
Suitable for all routine immunoassay analysers, ELISA methods and lateral flow devices.
Results can be submitted for both Anti-S and Anti-N methods.
Samples provided to challenge method cut-offs.
Interpretative reports based on clinical cases.

Frequency:
Monthly

Samples:
3 x 0.5mL

Material:
Endogenous human serum / plasma

SARS-CoV-2 Antibody Programme
Analyte	Approx. Range Covered
Anti-S IgG Ab / Total Ab	Negative / Positive	<0.4 to 20,000 U/ml (Roche S)
Anti-N IgG Ab / Total Ab	Negative / Positive	0.07 to 170 U/mL (Roche N)
Overall Interpretation	Negative / Positive