Table 2. Demographic characteristics of the SCOPI sampling frame, invited study sample and study participants, Dublin and Sligo, Ireland, 22 June–16 July 2020 (n = 407,009).

Characteristics			PCRS sampling frame (n = 407,009)		Invited study samplea (n = 5,199)		Participants in seroprevalence component of studyb (n = 1,733)
County	Sex	Age (years)	n	%	n	%	n	%
Dublin	Male	12–19	32,956	9	200	6	42	5
		20–29	25,610	7	313	10	67	7
		30–39	28,318	7	374	12	78	9
		40–49	36,499	10	289	9	81	9
		50–59	31,148	8	225	7	69	8
		60–69	23,981	6	169	5	84	9
	Female	12–19	31,263	8	193	6	48	5
		20–29	31,942	8	325	10	80	9
		30–39	39,463	10	389	12	93	10
		40–49	41,835	11	296	9	108	12
		50–59	33,192	9	241	8	84	9
		60–69	27,613	7	186	6	79	9
Dublin total		12–69	383,820	100	3,200	100	913	100
Sligo	Male	12–19	1,912	8	150	8	50	6
		20–29	1,801	8	140	7	37	5
		30–39	1,685	7	181	9	51	6
		40–49	2,140	9	184	9	71	9
		50–59	2,003	9	177	9	71	9
		60–69	1,718	7	154	8	75	9
	Female	12–19	1,826	8	143	7	58	7
		20–29	1,852	8	145	7	56	7
		30–39	2,063	9	197	10	88	11
		40–49	2,245	10	187	9	97	12
		50–59	1,989	9	185	9	93	11
		60–69	1,955	8	156	8	73	9
Sligo total		12–69	23,189	100	1,999	100	820	100

PCRS: Health Service Executive Primary Care Reimbursement Service. SCOPI: The Study to Investigate COVID-19 (coronavirus disease) Infection in People Living in Ireland.

^a Reflected county population by age and sex.

^b Of the invited participants who completed the SCOPI questionnaire, this subset also provided a blood specimen.