Table 1.
Characteristics of Study Participants at Baseline
| Characteristic | Participants Tested Using ELISA and sVNT | Random Subset of 20 Participants Tested Using ELISA, sVNT, and PRNT |
|---|---|---|
| (N = 312) | (N = 20) | |
| n (%) | n (%) | |
| Female | 120 (38) | 9 (45) |
| Age (median, IQR), years | 54 (47–62) | 55 (47–64) |
| Ethnicity | ||
| ȃChinese | 306 (98) | 20 (100) |
| Obesity (for Asian populations), body mass index | ||
| ȃUnderweight (<18.5) | 6 (2) | 0 (0) |
| ȃNormal (18.5–22.9) | 114 (37) | 5 (25) |
| ȃOverweight (23.0–24.9) | 84 (27) | 7 (35) |
| ȃObese (≥25.0) | 108 (35) | 8 (40) |
| Chronic medical conditions | ||
| ȃAny | 98 (32) | 6 (30) |
| ȃLung disease, including chronic obstructive pulmonary disease and asthma | 1 (0) | 0 (0) |
| ȃHeart disease | 7 (2) | 0 (0) |
| ȃHypertension | 57 (18) | 5 (25) |
| ȃDiabetes | 22 (7) | 1 (5) |
| ȃHypercholesterolemia | 42 (13) | 3 (15) |
| ȃKidney disease | 4 (1) | 0 (0) |
| ȃLiver disease | 4 (1) | 1 (5) |
| ȃCancer | 5 (2) | 1 (5) |
| Prior COVID-19 vaccination | ||
| ȃ2-dose CoronaVac (Sinovac) | 305 (98) | 20 (100) |
| ȃ2-dose BIBP (Sinopharm) | 7 (2) | 0 (0) |
| Days between first and second dose of COVID-19 vaccination, median (IQR) | 28 (28–29) | 28 (28–29) |
| Days between second and third (study) dose of COVID-19 vaccination, median (IQR) | 206 (192–217) | 197 (172–208) |
| Smoking | ||
| ȃEver | 33 (11) | 5 (25) |
| ȃCurrent | 22 (7) | 3 (15) |
We enrolled 315 adults who previously received 2 doses of inactivated COVID-19 vaccine and administered the BNT162b2 vaccine as a third vaccine dose. Among them, ELISA and sVNT against ancestral severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) virus were performed in paired day 0 and day 28 sera available from 312 vaccinated participants, and we randomly selected 20 participants and also performed PRNT against the ancestral SARS-CoV-2 virus and the Omicron variant.
Abbreviations: COVID-19, coronavirus disease 2019; ELISA, enzyme-linked immunosorbent assay; IQR, interquartile range; PRNT, plaque reduction neutralization test; sVNT, surrogate virus neutralization test.