Baseline characteristics of study population
| Variable | Overall (N=138) | BNT162b2 (N=101) | CoronaVac (N=37) | P value |
| Characteristics | ||||
| Age, years, (median (IQR)) | 47 (31.2–55.0) | 42 (29.0–53.0) | 55 (44.0–57.0) | 0.003 |
| Female* | 93 (67.9) | 65 (65.0) | 28 (75.7) | 0.304 |
| BMI, kg/m2, (median (IQR)) | 21.8 (20.2–24.5) | 21.8 (20.1–24.6) | 22.2 (20.4–23.7) | 0.946 |
| Overweight or obese† | 53 (38.7) | 38 (38.0) | 15 (40.5) | 0.844 |
| Obese† | 27 (19.7) | 22 (22.0) | 5 (13.5) | 0.338 |
| Presence of comorbidity | ||||
| Hypertension | 14 (10.1) | 7 (6.9) | 7 (18.9) | 0.055 |
| Diabetes mellitus | 4 (2.9) | 3 (3.0) | 1 (2.7) | 1.000 |
| Allergy ever | 49 (35.5) | 40 (39.6) | 9 (24.3) | 0.111 |
| Diarrhoea (past 3 months to current) | 55 (40.4) | 42 (42.0) | 13 (36.1) | 0.560 |
| Other comorbidities‡ | 15 (10.9) | 13 (12.9) | 2 (5.4) | 0.354 |
| Current medication | ||||
| Antibiotic intake (past 3 months and/or currently) | 6 (4.3) | 6 (5.9) | 0 (0.0) | 0.192 |
| Hormone therapy | 4 (2.9) | 4 (4.0) | 0 (0.0) | 0.574 |
| Immunomodulator | 3 (2.2) | 3 (3.0) | 0 (0.0) | 0.564 |
| Probiotics | 18 (13.1) | 12 (12.0) | 6 (16.2) | 0.572 |
| Vaccination in the past year | 53 (38.7) | 38 (38.0) | 15 (40.5) | 0.844 |
| Dietary habit | ||||
| Vegetarian | 1 (1.0) | 1 (1.0) | 0 (0.0) | 1.000 |
| Diet change during vaccination | 0 (0.0) | 0 (0.0) | 0 (0.0) | – |
| Alcohol intake (within 2 weeks prior to first vaccine dose) | 31 (22.5) | 25 (24.8) | 6 (16.2) | 0.361 |
| Exercise | ||||
| Regular exercise (strenuous/moderate) | 86 (62.3) | 62 (61.4) | 24 (64.9) | 0.843 |
| SARS-CoV-2 antibody response | ||||
| AUC of spike RBD IgG level (median (IQR))§ | 7889.5 (3110.8–9588.5) | 8696.0 (7628.0–11048.0) | 1725.0 (1418.0–2459.0) | <0.001 |
| sVNT (>60%) | 116 (84.1) | 100 (99.0) | 16 (43.2) | <0.001 |
| sVNT (inhibition %) (median (IQR)) | 93.9 (79.7–95.9) | 95.2 (92.1–96.4) | 57.6 (42.1–69.3) | <0.001 |
| Any adverse events¶ | ||||
| After the first dose | 116 (84.7) | 93 (93.0) | 23 (62.2) | <0.001 |
| After the second dose | 120 (87.6) | 95 (95.0) | 25 (67.6) | <0.001 |
Categorical data are presented as number (percentage) and continuous data as median (IQR). Within-group valid percentages are shown.
*One participant requested concealment of gender.
†BMI between 23.0 and 25.0 kg/m2 is classified as overweight and BMI above 25.0 kg/m2 is classified as obese.
‡Any other comorbidities: asthma, depression, eczema, high cholesterol, systemic lupus erythematosus, attention deficit hyperactivity disorder.
§Plasma IgG antibody binding to SARS-Cov-2 RBD was reported as area under the curve.
¶Any adverse events: injection site pain/burn, fatigue, fever, injection site swelling/pruritus/erythema/induration, myalgia, drowsiness, headache, chills, dizziness, arthralgia, loss of appetite, abdominal pain, rhinorrhea, sore throat, diarrhoea, pruritus, coughing, constipation, abdominal distension, nausea, flushing, hypersensitivity, muscle spasms, nasal congestion, oedema, vomiting, tremor, eyelid oedema, nosebleeds, hyposmia, ocular congestion, low back pain, increase of appetite, muscle pain, rib pain, eyes pain, palpitations.
AUC, area under the curve; BMI, body mass index; DM, diabetes mellitus; RBD, receptor-binding domain; sVNT, surrogate virus neutralisation test.