Table 1. Demographic Characteristics of the Study Sample^a.

Characteristics	Patients, %
	Total (N = 164 205)	Control	Intervention
		0 Reminders (n = 41 070)	1 Reminder (n = 41 055)	2 Reminders (n = 41 046)	3 Reminders (n = 41 034)
Age group, y
0.5-17	7.4	7.3	7.4	7.4	7.3
18-64	74.0	73.8	73.9	74.1	74.0
≥65	18.7	18.8	18.6	18.5	18.7
Female	58.3	58.4	58.3	58.2	58.4
Insurance
Private	85.2	85.1	85.3	85.2	85.1
Public	13.5	13.5	13.4	13.6	13.6
Other or unknown	1.3	1.4	1.3	1.3	1.3
Race
White	57.3	57.3	57.5	57.2	57.1
Black	4.6	4.4	4.6	4.7	4.8
Asian	10.3	10.1	10.4	10.3	10.3
Other or unknown	27.8	28.2	27.6	27.7	27.9
Hispanic ethnicity	9.6	9.5	9.6	9.8	9.6
Received influenza vaccination in prior 2 y	46.9	46.9	46.7	46.7	47.0

^aAll information was obtained from the electronic health records.