Table 4 Subgroup analysis (COVID-19 vs. general population) of HR (95% CI) of the post-acute respiratory sequelae or acute respiratory complications after SARS-CoV-2 infection stratified by vaccination, COVID-19 severity, and SARS-CoV-2 strain in the cohort of South Korea (main)

From: Acute and post-acute respiratory complications of SARS-CoV-2 infection: population-based cohort study in South Korea and Japan

Variable

 

HR (95% CI)

Events/total, n/N (%)

Model 1*

Model 2†

Post-acute respiratory sequelae

 Number of SARS-CoV-2 vaccinations

  Non-infected control∥

16,122/1,918,150 (0.84)

0.62 (0.60-0.65)

0.60 (0.58-0.62)

  COVID-19 without SARS-CoV-2 vaccination

4331/200,539 (2.16)

1.0 (reference)

1.0 (reference)

  COVID-19 after SARS-CoV-2 vaccination received once

493/38,852 (1.27)

0.90 (0.82-0.99)

0.85 (0.77-0.94)

  COVID-19 after SARS-CoV-2 vaccination received twice or more

468/155,207 (0.30)

0.69 (0.62-0.76)

0.64 (0.57-0.71)

 Type of SARS-CoV-2 vaccinations

  Non-infected control∥

16,122/1,918,150 (0.84)

0.62 (0.60-0.65)

0.60 (0.58-0.62)

  COVID-19 without SARS-CoV-2 vaccination

4331/200,539 (2.16)

1.0 (reference)

1.0 (reference)

  COVID-19 with viral vector SARS-CoV-2 vaccination

465/109,066 (0.43)

1.12 (1.01-1.23)

0.99 (0.90-1.10)

  COVID-19 with mRNA SARS-CoV-2 vaccination

477/66,891 (0.71)

1.20 (1.09-1.33)

1.11 (0.99-1.22)

  COVID-19 with both types of SARS-CoV-2 vaccination

19/18,102 (0.10)

0.74 (0.47-1.16)

0.66 (0.42-1.03)

 COVID-19 severity

  Non-infected control∥

16,122/1,918,150 (0.84)

1.0 (reference)

1.0 (reference)

  Mild COVID-19

3492/340,813 (1.02)

1.28 (1.24-1.33)

1.37 (1.32-1.43)

  Moderate to severe COVID-19

1800/53,785 (3.35)

3.60 (3.43-3.78)

3.20 (3.03-3.38)

 Original strain of SARS-CoV-2 (overall population)

  Non-infected control before the delta-dominant phase§

11,667/594,134 (1.96)

1.0 (reference)

1.0 (reference)

  Infection with original strain

3649/121,521 (3.00)

1.58 (1.52-1.64)

1.59 (1.52-1.66)

 Delta variant of SARS-CoV-2 (overall population)

  Non-infected control during the delta-dominant phase§

4455/1,324,016 (0.34)

1.0 (reference)

1.0 (reference)

  Infection with delta variant

1643/273,077 (0.60)

1.81 (1.71-1.92)

1.94 (1.81-2.08)

Acute respiratory complications

 Number of SARS-CoV-2 vaccinations

  Non-infected control∥

311/1,918,150 (0.016)

0.07 (0.06-0.08)

0.08 (0.06-0.09)

  COVID-19 without SARS-CoV-2 vaccination

415/200,539 (0.21)

1.0 (reference)

1.0 (reference)

  COVID-19 after SARS-CoV-2 vaccination received once

56/38,852 (0.14)

0.62 (0.47-0.83)

0.51 (0.38-0.68)

  COVID-19 after SARS-CoV-2 vaccination received twice or more

147/155,207 (0.09)

0.32 (0.26-0.39)

0.24 (0.19-0.30)

 Type of SARS-CoV-2 vaccinations

  Non-infected control∥

311/1,918,150 (0.016)

0.07 (0.06-0.08)

0.08 (0.06-0.09)

  COVID-19 without SARS-CoV-2 vaccination

415/200,539 (0.21)

1.0 (reference)

1.0 (reference)

  COVID-19 with viral vector SARS-CoV-2 vaccination

79/109,066 (0.072)

0.44 (0.34-0.56)

0.36 (0.28-0.47)

  COVID-19 with mRNA SARS-CoV-2 vaccination

117/66,891 (0.17)

0.40 (0.32-0.50)

0.42 (0.33-0.53)

  COVID-19 with both types of SARS-CoV-2 vaccination

7/18,102 (0.039)

0.19 (0.09-0.41)

0.18 (0.08-0.38)

 COVID-19 severity

  Non-infected control∥

311/1,918,150 (0.016)

1.0 (reference)

1.0 (reference)

  Mild COVID-19

50/340,813 (0.015)

0.95 (0.71-1.28)

0.99 (0.73-1.34)

  Moderate to severe COVID-19

568/53,783 (1.06)

51.18 (44.38-59.02)

39.54 (33.54-46.62)

 Original strain of SARS-CoV-2 (overall population)

  Non-infected control before the delta-dominant phase§

110/594,134 (0.019)

1.0 (reference)

1.0 (reference)

  Infection with original strain

230/121,521 (0.19)

10.27 (8.18-12.88)

9.21 (7.19-11.80)

 Delta variant of SARS-CoV-2 (overall population)

  Non-infected control during the delta-dominant phase§

201/1,324,016 (0.015)

1.0 (reference)

1.0 (reference)

  Infection with delta variant

388/273,077 (0.14)

9.39 (7.92-11.14)

7.44 (6.13-9.03)

  1. CCI, Charlson comorbidity index; CI, confidence interval; HR, hazard ratio; SARS-CoV-2, severe acute respiratory syndrome coronavirus 2.
  2. Bold indicates that hazard ratio is statistically significant (P < 0.05).
  3. ∥HR of the non-infected control represents the risk of respiratory diseases, and HRs of patients with COVID-19 indicate the risk of post-acute respiratory complications following SARS-CoV-2 infection.
  4. § Only 1:5–matched comparators in each patient group at the same index date were included to reduce immortal time bias.
  5. *Model 1: Adjusted for age (20–39, 40–59, and ≥60 years) and sex.
  6. †Model 2: Adjusted for age (20–39, 40–59, and ≥60 years); sex, household income (low income, middle income, and high income); region of residence (urban and rural); CCI score (0, 1, and ≥2); obesity (underweight [<18.5 kg/m2], normal [18.5–22.9 kg/m2]; overweight [23.0–24.9 kg/m2], obese [≥25.0 kg/m2], and unknown); blood pressure (systolic blood pressure <140 mmHg and diastolic blood pressure < 90 mmHg, systolic blood pressure ≥ 140 mmHg or diastolic blood pressure ≥90 mmHg, and unknown); fasting blood glucose (<100, ≥100 mg/dL, and unknown); serum total cholesterol (<200, 200–239, ≥240 mg/dL, and unknown); glomerular filtration rate (<60, 60–89, ≥90 mL/min/1.73 m2, and unknown); smoking status (never, former, current smoker, and unknown); alcoholic drinks (<1, 1–2, 3–4, ≥5 days per week, and unknown); aerobic physical activity (sufficient, insufficient, and unknown); previous history of cardiovascular disease, and chronic kidney disease; history of medication use for diabetes mellitus, dyslipidemia, and hypertension; and strain of SARS-CoV-2 (original and delta).
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