Table 2.

SARS-CoV-2 anti-RBD total antibody seroprevalence in blood donors by participant characteristics and location

Variable	Category	Sample size	Seropositive (frequency)	Unadjusted (%)	Estimate	SE	z value	p value
Intercept					− 6.12	0.76	− 8.11	< 0.001
Gender	Female	1393	407	29.2%	Ref	Ref	Ref	Ref
	Male	3692	994	26.9%	0.05	0.09	0.58	0.56
Age group	15–19§	912	265	29.1%	Ref	Ref	Ref	Ref
	20–29	2465	684	27.7%	− 0.04	0.11	− 0.32	0.75
	30–39	1068	284	26.6%	− 0.01	0.13	− 0.06	0.95
	40–49	596	154	25.8%	0.16	0.15	1.04	0.3
	50+	44	14	31.8%	0.2	0.38	0.53	0.6
Location	Balakaφ	1198	254	21.2%	Ref	Ref	Ref	Ref
	Blantyre	1351	416	30.8%	0.77	0.13	5.92	< 0.001*
	Lilongwe	1328	345	26.0%	0.6	0.13	4.56	< 0.001*
	Mzuzu	1208	386	32.0%	0.86	0.13	6.41	< 0.001*

This is an unweighted multivariable logistic regression model with sex, age group, location, and time as predictors

^§Recruitment limited to blood donors ≥15 years of age

*Significant based on p value < 0.05

^φBalaka was used as a reference as it is the only Malawi Blood Transfusion Service (MBTS) static site that directly covers the rural area