Table 2. Gamma GLM model for neutralising antibody levels, England, 22 April–12 May 2020 (n = 265).

Factor	Categorisation	Exp (par. est)	95% CI	p value
Age	Linear variablea	1.02	1.01–1.03	0.0001
Hospitalisation	Yes	2.25	1.52–3.32	p < 0.0001
	No	1	Reference
Ethnic group	Asian	Not done	Not done	0.64
	Other
	Unknown
	White
Gender	Female	1	Reference	p < 0.0001
	Male	2.41	1.86–3.14
Donor centre	Edgware	2.87	1.81–4.54	p < 0.0001
	Manchester	2.35	1.32–4.19
	Sheffield	0.81	0.50–1.33
	Tooting	1	Reference
	West End Donor Centre	1.99	1.38–2.87
	Other	1.26	0.88–1.80
Blood group	A	Not done	Not done	0.81
	B
	O
	AB
Previous blood donor	Yes	Not done	Not done	0.30
	No
Social deprivation indicatorb	Affluent achievers	0.65	0.42–1.02	0.06
	Rising prosperity	0.55	0.35–0.88
	Comfortable communities	0.60	0.37–0.98
	Financially stretched	0.47	0.27–0.82
	Urban adversity	1	Reference
Days since project began	Linear variable	1.04	1.02–1.07	0.001
Days since diagnosisc	Linear variable	0.94	0.92–0.96	p < 0.0001

CI: confidence interval; Exp (par. est): the exponentiated parameter estimates; GLM: generalised linear model.

^a A nonlinear term for age was tested but found to be non-significant (p = 0.25).

^b Social deprivation scores were calculated based on postcode and Acorn classification [14], which divides the population into five categories. Based on that model, ‘affluent achievers’ are the most financially successful and healthy people in the United Kingdom, ‘rising prosperity’ includes generally younger, well educated, and mostly prosperous people living in our major towns and cities, ‘comfortable communities’ are the middle graders in terms of social and financial wellbeing, whereas the ‘financially stretched’ group includes mostly people with modest lifestyles and less than average income and the ‘urban adversity’ group includes people who are experiencing the most difficult social and financial conditions.

^c A nonlinear term for ‘days since diagnosis’ was tested but found to be non-significant (p = 0.91).