Table 1 SARS-CoV-2 IgG antibody levels (Geometric Mean Titres) according to characteristics of HCW participants following COVID-19 vaccination (N = 1517)

Age groups in years

 16–29*

267 (17.6%)

1470 (1286–1679)

 30–39

425 (28.0%)

1112 (986–1256)

 40–49

360 (23.7%)

1319 (1151–1513)

 50–59

338 (22.3%)

1423 (1275–1589)

 60+

99 (6.5%)

1756 (1477–2087)

 Unknown

28 (1.8%)

833 (466–1487)

Gender

 Female

1112 (73.3%)

1344 (1251–1445)

 Male

397 (26.2%)

1233 (1105–1377)

 Non-Binary

4 (0.3%)

1769 (1131–2766)

 Unknown

4 (0.3%)

2167 (658–7134)

Previous laboratory-confirmed SARS-CoV-2 infection

 Yes, once

214 (14.1%)

1487 (1265–1747)

 Yes, > 1 reinfection

11 (0.7%)

1776 (970–3251)

Time since previous laboratory confirmed SARS-CoV-2 infection

 ≤ 3 months

58 (3.8%)

1507 (1103–2059)

 > 3 months

153 (10.1%)

1524 (1270–1829)

 unknown

14 (0.9%)

1227 (468–3220)

 No

1284 (84.6%)

1285 (1203–1372)

 Unknown

8 (0.5%)

1845 (937–3630)

Type of profession

 Nurse

467 (30.8%)

1309 (1167–1468)

 Physician

262 (17.3%)

1278 (1144–1428)

 Other allied health professionals

402 (26.5%)

1382 (1229–1555)

 Administration/other facility management

364 (24.0%)

1272 (1117–1449)

 Unknown

22 (1.5%)

1577 (879–2829)

Number of vaccine doses received

 Three times vaccinated (plus evidence of past SARS-CoV-2 infection)

79 (5.2%)

2204 (1919–2531)

 Three times vaccinated (no evidence of past SARS-CoV-2 infection)

1122 (74.0%)

1650 (1585–1717)

 Two times vaccinated (plus evidence of past SARS-CoV-2 infection)

98 (6.5%)

1755 (1433–2150)

 Two times vaccinated (no evidence of past SARS-CoV-2 infection)

101 (6.7%)

335 (258–434)

 One time vaccinated (plus evidence of past SARS-CoV-2 infection)**

32 (2.1%)

1059 (713–1573)

 One time vaccinated (no evidence of past SARS-CoV-2 infection)***

19 (1.3%)

394 (132–1176)

 Not vaccinated (plus evidence of past SARS-CoV-2 infection)

16 (1.1%)

171 (61–475)

 Not vaccinated (no evidence of past SARS-CoV-2 infection)

42 (2.8%)

69 (26–184)

 Unknown

8 (0.5%)

1845 (937–3630)

Combined SARS-CoV-2 vaccination and past infection exposures

 None

42 (2.8%)

69 (26–184)

 One exposure

34 (2.3%)

272 (128–578)

 Two exposures

133 (8.8%)

435 (345–549)

 Three exposures

1217 (80.6%)

1655 (1590–1722)

 Four exposures

79 (5.2%)

2260 (1962–2602)

 Five exposures

4 (0.3%)

2043 (1366–3056)

Type of specific vaccination received (among those three times vaccinated)

N = 1201

 2 doses BNT162b2 (3 weeks apart) + BNT162b2 booster

436 (36.3%)

1629 (1530–1734)

 2 doses BNT162b2 (6 weeks apart) + BNT162b2 booster

130 (10.8%)

2008 (1761–2291)

 1 dose ChAdOx1-S, 1 dose BNT162b2 + BNT162b2 booster

378 (31.5%)

1576 (1478–1681)

 2 doses ChAdOx1-S + BNT162b2 booster

159 (13.2%)

1699 (1505–1918)

 1 dose ChAdOx1-S, 1 dose BNT162b2 + mRNA-1273 booster

23 (1.9%)

2154 (1788–2595)

 2 doses mRNA-1273 + BNT162b2 booster

11 (0.9%)

1733 (1305–2300)

 2 doses BNT162b2 + mRNA-1273 booster

11 (0.9%)

3343 (2311–4837)

 2 doses ChAdOx1-S + mRNA-1273 booster

11 (0.9%)

3502 (2338–5246)

 Unknown/other vaccine scheme

42 (3.5%)

1472 (1244–1741)

Type of vaccination scheme received (among those three times vaccinated)

 Homologous COVID-19 vaccine scheme

566 (47.1%)

1710 (1615–1810)

 Heterologous COVID-19 vaccine scheme with mRNA-1273 booster

45 (3.7%)

2657 (2267–3114)

 Heterologous COVID-19 vaccine scheme with another booster

548 (45.6%)

1614 (1525–1709)

Time since last COVID-19 vaccine dose (among those three times vaccinated)

N = 1201

 < 30 days

78 (6.5%)

2151 (1698–2724)

 30–49 days

586 (48.8%)

1877 (1786–1971)

 50–69 days

299 (24.9%)

1627 (1510–1754)

 70–89 days

170 (14.2%)

1324 (1200–1461)

 ≥ 90 days

37 (3.1%)

1156 (876–1524)

 Unknown

31 (2.6%)

1249 (857–1821)