Effective April 6th, 2021, CPL will perform all antibody testing for the Nucleocapsid antigen of SARS-CoV-2 (the causative agent of COVID-19) using the Roche Elecsys Anti-SARS-CoV-2 chemiluminescent immunoassay (unit code 7304). This is a sandwich immunoassay format designed to select for high-affinity total anti-COVID-19 antibody (IgG, IgA and IgM). The IgG-only COVID-19 Nucleocapsid antigen immunoassay will be discontinued (unit code 7301).
The Elecsys SARS-CoV-2 Nucleocapsid total antibody assay is intended for use as an aid in identifying individuals with an adaptive immune response to SARS-CoV-2, indicating recent or prior infection. As previously, this test should not be used to diagnose acute SARS-CoV-2 infection for which PCR testing is available. The assay can detect seropositivity in 60.2% of patients within the first week after PCR confirmation and sensitivity rises to 99.5% by day 14. Specificity is among the highest of immunoassays at 99.8%, and there is no cross-reactivity with ordinary endemic common-cold coronavirus species (HKU1, NL63, OC43, etc). For testing performed beyond 100 days, the Elecsys total-antibody assay remains persistently positive, whereas the IgG-only antibody assays show decreased sensitivity for prior COVID-19 infection.
| UNIT CODE: | 7301 – TO BE DISCONTINUED | 7304 |
| REPORTING TITLE: | SARS–CoV–2 IgG Ab, N protein | SARS–CoV–2 Total Ab, N protein |
| SPECIMEN REQUIREMENTS: |
2 ML SERUM. ALLOW SST TO CLOT IN AN UPRIGHT POSITION FOR ATLEAST 30 MINUTES, THEN CENTRIFUGE SAMPLE WITHIN 2 HOURS OF COLLECTION. REFRIGERATE. SEE EXAMPLE REQUISTION/HISTORY SHEET LINK BELOW: COVID-19 Requisition: |
2 ML SERUM. ALLOW SST TO CLOT IN AN UPRIGHT POSITION FOR AT LEAST 30 MINUTES, THEN CENTRIFUGE SAMPLE WITHIN 2 HOURS OF COLLECTION. REFRIGERATE. SEE EXAMPLE REQUISTION/HISTORY SHEET LINK BELOW: COVID-19 Requisition: |
| TRANSPORT TEMPERATURE: | REFRIGERATED | REFRIGERATED |
| MINIMUM SPECIMEN VOLUME: | 1 ML SERUM OR EDTA PLASMA | 1 ML SERUM |
| METHODOLOGY: | CHEMILUMINESCENT MICROPARTICLE IMMUNOASSY (CMIA) | ELECTROCHEMILUMINESCENCE IMMUNOASSAY (ECLIA) |
| REF. RANGE AND UNITS OF MEASURE: |
< 1.4 = NEGATIVE ≥ 1.4 = POSITIVE |
COI < 1.0 NEGATIVE COI ≥ 1.0 POSITIVE |
| STABILITY: |
2 DAYS ROOM TEMPERATURE 7 DAYS REFRIGERATED 1 MONTH FROZEN |
3 DAYS ROOM TEMPERATURE 7 DAYS REFRIGERATED 28 DAYS FROZEN |
| CPT CODE: | 86769 | 86769 |
Reference:
Mohanraj D et al. Comparative assessment of SARS-CoV-2 serology in healthcare workers with Abbott Architect, Roche Elecsys and The Binding site ELISA immunoassays. medRxiv 2021.03.19.21253518; doi: https://doi.org/10.1101/2021.03.19.21253518