Table 3.
Comparison of conventional and surrogate SARS-CoV-2 VNT (the latter in singleplex format and with Wuhan S1 as antigen), using reference and standard sera provided by the European Centre for Disease Prevention and Control (ECDC) and the World Health Organization (WHO).
| cVNT | sVNT | ||
|---|---|---|---|
| ID | Control Serum/Plasma | Inhibition (%) | Inhibition (%) |
| (1:20) | (1:20) | ||
| EQA A | SARS-CoV-2 Abs (Hospitalized patient) | 100 * | 91 |
| EQA B | SARS-CoV-2 Abs (Mild infection) | 100 | 94 |
| EQA C | Negative pre-pandemic sera (Other human CoV) | 0 | 0 |
| EQA D | SARS-CoV-2 Abs (Hospitalized patient) | 100 | 97 |
| EQA E | Acute EBV/CMV sera (Other human CoV) | 0 | 0 |
| EQA F | Negative pre-pandemic sera (Other human CoV) | 0 | 0 |
| EQA G | SARS-CoV-2 Abs (Mild infection) | 100 | 80 |
| EQA H | SARS-CoV-2 Abs (Hospitalized patient) | 100 | 89 |
| JCR 017 | SARS-CoV-2 Abs (Standard) | 98 | 80 |
| JCR 018 | SARS-CoV-2 Abs (Standard) | 92 | 87 |
| 20/136 | SARS-CoV-2 Abs (Standard) | 100 | 96 |
| 20/140 (20/268) | SARS-CoV-2 Abs + NAbs (Lowest Ab levels) | 53 | 54 |
| 20/142 (20/268) | Negative human sera | 6 | 34 |
| 20/144 (20/268) | SARS-CoV-2 Abs + NAbs (Low Ab levels) | 92 | 50 |
| 20/148 (20/268) | SARS-CoV-2 Abs + NAbs (Mid Ab levels) | 97 | 86 |
| 20/150 (20/268) | SARS-CoV-2 Abs + NAbs (High Ab levels) | 100 | 96 |
EQA A–H—ECDC’s SARS-CoV-2 serological external quality assessment panel; JCR 017 and 018—ECDC’s SARS-CoV-2 serological standards; * 1:100; Abs—antibodies; NAbs—neutralizing antibodies; SARS-CoV-2—Severe acute respiratory syndrome coronavirus 2; CoV—coronavirus; EBV—Epstein-Barr virus; CMV—Cytomegalovirus; grey—above positivity cut-off (50% (cVNT), 36% (sVNT)).