TABLE 4.
Analysis of discrepant results among five SARS-CoV-2 antibody assays before and after the 1st dose of the AstraZeneca vaccinea
| Category of discrepancy | No. (%) of samples | Median (range) antibody level by the following assay: |
||||
|---|---|---|---|---|---|---|
| Roche (U/ml) | Abbott (AU/ml) | Siemens (index) | GenScript (%) | SD biosensor V1 (%) | ||
| Roche only positive | 2 (2.2) | 58.6 (2.3–115.0) | 36.4 (36.0–36.8) | 0.5 (0.0–1.0) | 17.0 (9.9–24.1) | 13.4 (4.6–22.2) |
| Abbott only positive | 5 (5.6) | 0.5 (0.0–1.0) | 82.1 (61.0–267.3) | 0.5 (0.4–0.8) | 21.9 (14.0–27.6) | 26.8 (24.3–29.7) |
| Siemens only positive | 1 (1.1) | 0.7 | 35.4 | 1.48 | 10.1 | 21.7 |
| GenScript only positive | 0 | – | – | – | – | – |
| SD Biosensor only positive (V1 positive or V2 positive) | 2 (2.2) | 0.4 (0.4–0.4) | 11.2 (0.6–21.7) | 0.2 (0.1–0.3) | 13.6 (7.5–19.7) | 38.2 (33.5–41.1) |
| Roche only negative | 1 (1.1) | 0.7 | 182.1 | 5.54 | 32.3 | 79.9 |
| Abbott only negative | 0 | – | – | – | – | – |
| Siemens only negative | 5 (5.6) | 1.7 (0.9–23.0) | 86.3 (76.0–150.2) | 0.7 (0.5–1.0) | 35.6 (31.6–60.3) | 68.3 (62.6–90.2) |
| GenScript only negative | 24 (26.7) | 4.5 (1.1–114.0) | 193.1 (107.0–950.8) | 1.7 (1.1–5.1) | 25.8 (13.0–30.0) | 65.0 (41.6–89.3) |
| SD Biosensor only negative | 0 | – | – | – | – | – |
| Others | 50 (55.6) | |||||
| Total | 90 (100) | 1.5 (0.4–143.0) | 115.1 (0.6–1347.6) | 0.9 (0.0–15.5) | 24.2 (0.1–72.9) | 54.2 (4.6–90.2) |
a
Cutoff values are 0.8 U/ml for the Roche assay, 50 AU/ml for the Abbott assay, an index of 1.0 for the Siemens assay, 30% for the GenScript assay, and 30% for the SD Biosensor V1 assay.