Table 3.

Association between the peak anti-spike IgG antibody levels 14–84 days post-second vaccination with each characteristic from the univariable model and multivariable model

	Univariable				Multivariable
	Coefficient	P value	95% CI		Coefficient	P value	95% CI
Age
Per 10-year older	−0.034	0.002	−0.06	−0.01	−0.03	<0.001	−0.05	−0.01
Sex
Female	1 (ref)
Male	0.02	0.6	−0.06	0.09	−0.04	0.14	−0.09	0.01
Ethnicity
White	1 (ref)
Asian	0.01	0.7	−0.06	0.09
Black	−0.22	0.009	−0.38	−0.05
Mixed	0.07	0.5	−0.13	0.26
Other	−0.07	0.4	−0.23	0.09
Role
Nurse/HCA	1 (ref)
Doctor	0.1	0.1	−0.02	0.22
Administrative staff	0.07	0.1	−0.01	0.15
OT/PT/SLT	0.11	0.1	−0.03	0.26
Laboratory staff	0.24	0.002	0.09	0.39
Porter or domestic worker	−0.23	0.03	−0.44	−0.03
Medical or nursing student	0.07	0.7	−0.26	0.4
Other	−0.06	0.1	−0.14	0.01
BMI
<16	−0.13	0.7	−0.8	0.53
16–24.9	1 (ref)
25–29.9	−0.06	0.1	−0.12	0.01
30–34.9	0.01	0.9	−0.08	0.09
35–39.9	0.01	0.9	−0.12	0.14
40+	0.05	0.5	−0.09	0.19
Comorbidity
Yes vs no
Smoking	−0.17	0.003	−0.29	−0.06	−0.06	0.12	−0.14	0.02
Pregnant	0.13	0.3	−0.11	0.37
Asthma	0.005	0.9	−0.15	0.04
Hypertension	−0.06	0.2	−0.15	0.03	−0.06	0.09	−0.12	0.01
Thyroid disorder (excluding malignancy)	0.01	0.9	−0.09	0.11	0.05	0.13	−0.02	0.12
Diabetes	−0.14	0.03	−0.26	−0.01	−0.14	<0.001	−0.22	−0.05
Immunosuppression	−0.38	<0.001	−0.51	−0.25	−0.22	<0.001	−0.31	−0.13
Psoriasis	−0.13	0.1	−0.3	0.04
Heart disease	0.05	0.6	−0.14	0.25
Non-haematological malignancy	0.14	0.1	−0.04	0.32	0.13	0.04	0.01	0.25
Rheumatological disorder	−0.28	0.01	−0.5	−0.06
Respiratory disease (excluding asthma)	−0.22	0.02	−0.41	−0.03	−0.17	0.01	−0.3	−0.04
Haematological disease (excluding malignancy)	0.06	0.6	−0.14	0.25
Liver disease	−0.03	0.9	−0.38	0.32
Neurological disorder	−0.001	0.9	−0.33	0.33
CKD stage 3, 4 or 5	−0.84	<0.001	−1.3	−0.37
Lupus	−0.68	0.002	−1.1	−0.24
Splenic disorder (excluding traumatic splenectomy)	−0.42	0.2	–1	0.15
Haematological malignancy	0.13	0.7	−0.53	0.79
Organ transplant	−3.06	<0.001	−3.55	−2.57	−2.66	<0.001	−3.01	−2.31
Vaccination
BNT162b2/BNT162b2
ChAdOx1/ChAdOx1	−0.9	<0.001	−0.95	−0.85	−0.91	<0.001	−0.96	−0.87
Evidence of COVID-19 infection at baseline (yes vs no)	0.25	<0.001	0.18	0.33	0.29	<0.001	0.24	0.34
COVID-age score
Per 10 score higher	−0.05	<0.001	−0.06	−0.03

Bold indicates a significant p value of <0.05. The outcome was modelled in log₁₀ scale. Variables in the multivariable model were selected using backward selection by Akaike information criteria.

BMI, body mass index; CKD, chronic kidney disease; HCA, healthcare assistant; OT/PT/SLT, occupational therapist, physiotherapist, and speech and language therapist.