Table 2.
Relationship Between SARS-CoV Neutralizing Antibodies and Onset of Symptoms
| Onset, d | PRNT Tested | Titer | % Neutralizers at FDA Minimal Level | % Neutralizers at FDA Recommended Level | |||
|---|---|---|---|---|---|---|---|
| <80 | 80 | 160 | >320 | ||||
| SARS-CoV-2 PRNT50 Titers | |||||||
| 11–15 | 12 | 5 | 4 | 2 | 1 | 58.3 | 25.0 |
| 16–20 | 58 | 28 | 12 | 7 | 11 | 51.7 | 31.0 |
| 21–25 | 54 | 6 | 8 | 17 | 23 | 88.9 | 74.1 |
| 26–30 | 53 | 2 | 10 | 7 | 34 | 96.2 | 77.4 |
| 31–35 | 41 | 0 | 3 | 8 | 30 | 100 | 92.7 |
| 36–40 | 34 | 1 | 5 | 7 | 21 | 97.1 | 82.4 |
| >40 | 48 | 3 | 12 | 10 | 23 | 93.8 | 68.8 |
| SARS-CoV-2 PRNT90 Titers | |||||||
| 11–15 | 12 | 11 | 0 | 0 | 1 | 8.3 | 8.3 |
| 16–20 | 59 | 42 | 8 | 2 | 7 | 28.8 | 15.3 |
| 21–25 | 54 | 19 | 15 | 13 | 7 | 64.8 | 37.0 |
| 26–30 | 53 | 12 | 16 | 13 | 12 | 77.4 | 47.2 |
| 31–35 | 41 | 7 | 12 | 10 | 12 | 82.9 | 53.7 |
| 36–40 | 34 | 13 | 13 | 3 | 5 | 61.8 | 23.5 |
| >40 | 48 | 28 | 10 | 5 | 5 | 41.7 | 20.8 |
Antibody-positive serum specimens from COVID-19 convalescent patients with onset of symptom and blood collection information were tested. All of the specimens were assessed for either SARS-CoV RBD (Mount Sinai) and SARS-CoV N or SARS-CoV N plus RBD (Mount Sinai, Westchester) reactivity using a microsphere immunoassay. The neutralization titer is the inverse endpoint dilution of sera that could neutralize 50% (top) or 90% (bottom) of viral plaque formation. % Neutralizers at FDA recommended level have a neutralizing titer of 160 or greater. % Neutralizers at FDA minimal level have a neutralizing titer of 80 or greater.
Abbreviations: FDA, Food and Drug Administration; PRNT, plaque reduction neutralization tests; RBD, receptor-binding domain; SARS-CoV-2, severe acute respiratory syndrome coronavirus 2.