Table 5 Unadjusted and adjusted hazard ratios (HRs with 95% CIs) of hospitalisation or death due to COVID-19 after at least two doses of COVID-19 vaccine for individuals in the primary care cohort (models D and E)

From: Association between antibody responses post-vaccination and severe COVID-19 outcomes in Scotland

Model

Risk Factors (Reference)

Hospitalisation/Death Hazard Ratios (95% CI)

Unadjusted

Adjusted

D

Testing IgG Negative (No)

Yes

4.82 (3.07–7.59)

3.68 (2.28–5.94)

Number of Risk Groups (0)

1

1.33 (0.68–2.62)

1.66 (0.82–3.38)

2

2.86 (1.47–5.56)

3.14 (1.53–6.42)

3-4

6.23 (3.39–11.44)

5.24 (2.64–10.41)

5+

16.67 (8.22 – 33.81)

13.37 (6.05 – 29.53)

E

IgG Quantile (High [230-1999 BAU/ml])

Undetectable ( < 4.8 BAU/ml)

16.51 (8.74–31.19)

9.21 (4.63 – 18.29)

Very Low (4.8-33.7 BAU/ml)

2.55 (1.31–4.97)

2.15 (1.08 – 4.26)

Low (33.8-229 BAU/ml)

1.55 (0.89–2.70)

1.57 (0.89 – 2.77)

Very High ( ≥ 2000 BAU/ml])

0.42 (0.19–0.93)

0.33 (0.15 – 0.74)

Haematological Cancer (No)

7.86 (3.43–18.03)

2.79 (1.15 – 6.76)

Coronary Heart Disease (No)

3.80 (2.36–6.13)

1.64 (0.97 – 2.76)

Pulmonary Hypertension (No)

13.02 (5.27–32.14)

4.99 (1.95 – 12.75)

Chronic Kidney Disease (No)

4.90 (3.09–7.77)

2.21 (1.33–3.65)

  1. In model D, the qualitative IgG test result (positive or negative) was used along with the number of risk groups as covariates. In model E, we use quantiles of the antibody IgG levels with high risk (of COVID-19 severe outcomes) groups decoupled from all other risk groups.
  2. ORs were also adjusted for: the number of additional risk groups (model E only), age, sex, BMI and the number of subsequent vaccinations. The hospitalisation/death rate of double-vaccinated-serology-tested individuals (severe outcomes) was 0.5% of the total primary care attendees (n = 85).
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