Table 2 Distribution of pre-COVID demographics by different patterns of COVID-19 diagnosis using clinical assessment and real-time reverse transcriptase-polymerase chain reaction (RT-PCR)

Age, years

 ≤ 30

478 (81.15)

 < 0.001

362 (61.46)

 < 0.001

251 (42.61)

0.001

227 (38.54)

 < 0.001

111 (18.85)

 < 0.001

31–44

1,492 (83.12)

1,116 (62.17)

813 (45.29)

579 (37.83)

303 (16.88)

45–60

2,188 (87.84)

1,548 (62.14)

1,245 (49.98)

943 (37.86)

303 (12.16)

 > 60

1,547 (91.81)

910 (54.01)

772 (45.28)

775 (45.99)

138 (8.19)

Gender

Female

2,449 (86.69)

0.563

1,784 (63.15)

 < 0.001

1,408 (49.84)

 < 0.001

1,041 (36.85)

 < 0.001

376 (13.31)

0.563

Male

3,256 (87.18)

2,152 (57.62)

1,673 (44.79)

1,583 (42.38)

855 (12.82)

Smoking

Non-smoker

3,696 (86.60)

0.15

2,634 (61.72)

 < 0.001

2,062 (48.31)

 < 0.001

1,634 (38.28)

 < 0.001

572 (13.40)

0.15

Ex-smoker

1,261 (88.49)

834 (58.53)

670 (47.02)

591 (41.47)

164 (11.51)

Smoker (or stopped < 1year ago)

748 (86.27)

468 (53.98)

349 (40.25)

399 (46.02)

119 (13.73)

Body mass index (BMI), kg/m2

 < 25

2,732 (84.87)

 < 0.001

1,953 (60.67)

0.206

1,466 (45.54)

0.027

1,266 (39.33)

0.206

487 (15.13)

 < 0.001

25–29.99…

2,163 (89.09)

1,460 (60.08)

1,194 (49.09)

970 (39.92)

267 (10.99)

 ≥ 30

810 (88.91)

523 (57.41)

422 (46.32)

388 (42.59)

101 (11.09)

Raised on a farm

No

5,141 (86.67)

0.026

3,598 (60.65)

0.001

2,807 (47.32)

0.078

2,334 (39.35)

0.001

791 (13.33)

0.026

Yes

564 (89.81)

338 (53.82)

274 (43.63)

290 (46.18)

64 (10.19)

Rural residence during childhood

No

4,075 (86.50)

0.073

2,829 (60.05)

0.893

2,193 (46.55)

0.281

1,882 (39.95)

0.893

636 (13.50)

0.073

Yes

1,630 (88.16)

1,107 (59.87)

888 (48.03)

742 (40.31)

219 (11.84)

Highest education attained

Less than high school

669 (91.64)

 < 0.001

396 (54.25)

0.003

335 (45.89)

0.809

334 (45.75)

0.003

61 (8.36)

 < 0.001

High school

2,721 (86.55)

1,900 (60.43)

1,477 (46.98)

1,244 (39.57)

423 (13.45)

Tertiary education

2,315 (86.19)

1,640 (61.06)

1,269 (47.24)

1,046 (38.94)

371 (13.81)

Social class classification†

1 (managers)

333 (90.49)

0.035

226 (61.41)

0.012

191 (51.90)

 < 0.001

142 (38.59)

0.012

35 (9.51)

0.035

2 (professionals)

1,159 (85.60)

823 (60.78)

628 (46.38)

531 (39.22)

195 (14.40)

3 (technicians and associate professionals)

791 (87.31)

588 (64.90)

473 (52.21)

318 (35.10)

115 (12.69)

4 (office support workers)

425 (88.91)

278 (58.16)

225 (47.07)

200 (41.84)

53 (11.09)

5 (service and sale workers)

1,346 (86.45)

917 (58.90)

706 (45.34)

630 (41.10)

211 (13.55)

6 (skilled agriculture/forestry/fishery workers)

173 (81.99)

125 (59.24)

87 (41.23)

86 (40.76)

38 (18.01)

7 (craft and related trade workers)

322 (87.98)

231 (63.11)

187 (51.09)

135 (36.89)

44 (12.02)

8 (plant and machine operators/assemblers)

251 (90.61)

163 (58.84)

137 (49.46)

114 (41.16)

26 (9.39)

9 (elementary occupations)

905 (86.77)

585 (56.09)

447 (42.86)

458 (43.91)

138 (13.23)

0 (military personnel)

0 (0)

0 (0)

0 (0)

0 (0)

0 (0)

Clinician-diagnosed COPD

No

5,558 (86.83)

0.038

3,862 (60.33)

 < 0.001

3,019 (47.16)

0.041

2,539 (39.67)

 < 0.001

843 (13.17)

0.038

Yes

147 (92.45)

74 (46.54)

62 (38.99)

85 (53.46)

12 (7.55)

Clinician-diagnosed asthma

No

5,125 (87.10)

0.341

3,558 (60.47)

0.022

2,799 (47.57)

0.004

2,326 (39.53)

0.022

759 (12.90)

0.341

Yes

580 (85.80)

378 (55.92)

282 (41.72)

298 (44.08)

96 (14.20)

Allergic asthma (asthma + rhinitis)

No

5,168 (86.99)

0.868

3,586 (60.36)

0.065

2,813 (47.35)

0.054

2,355 (39.64)

0.065

773 (13.01)

0.868

Yes

537 (86.75)

350 (56.54)

268 (43.30)

269 (43.46)

82 (13.25)

Any respiratory symptom‡

No

3,912 (86.55)

0.135

2,801 (61.97)

 < 0.001

2,193 (48.52)

 < 0.001

1,719 (38.03)

 < 0.001

608 (13.45)

0.135

Yes

1,793 (87.89)

1,135 (55.64)

888 (43.53)

905 (44.36)

247 (12.11)

Number of comorbidities§

0

2,224 (85.47)

0.006

1,639 (62.99)

 < 0.001

1,261 (48.46)

0.027

963 (37.01)

 < 0.001

378 (14.53)

0.006

1

1,662 (87.20)

1,149 (60.28)

905 (47.48)

757 (39.72)

244 (12.80)

 ≥ 2

1,819 (88.65)

1,148 (55.95)

915 (44.59)

904 (44.05)

233 (11.35)

Number of "severe" comorbidities (COPD, diabetes)

0

5,307 (86.70)

0.018

3,706 (60.55)

0.002

2,892 (47.25)

0.235

2,415 (39.45)

0.002

814 (13.30)

0.018

1

377 (91.28)

214 (51.82)

178 (43.10)

199 (48.18)

36 (8.72)

2

21 (80.77)

16 (61.54)

11 (42.31)

10 (38.46)

5 (19.23)

Number of "moderately severe" comorbidities (asthma, hypertension)

0

4,309 (86.23)

0.003

3,077 (61.58)

 < 0.001

2,389 (47.81)

0.015

1,920 (38.42)

 < 0.001

688 (13.77)

0.003

1

1,269 (88.99)

797 (55.89)

640 (44.88)

629 (44.11)

157 (11.01)

2

127 (92.70)

62 (45.26)

52 (37.96)

75 (54.74)

10 (7.30)

Number of "mild" comorbidities (eczema, rhinitis, sleep disorder)

0

2,732 (86.43)

0.409

1,949 (61.66)

0.001

1,520 (48.09)

0.015

1,212 (38.34)

0.001

429 (13.57)

0.409

1

1,890 (87.26)

1,303 (60.16)

1,027 (47.41)

863 (39.84)

276 (12.74)

 ≥ 2

1,083 (87.83)

684 (55.47)

534 (43.31)

549 (44.53)

150 (12.17)