Table 2.

Characteristics of hospitalized infants < 6 months of age by maternal influenza vaccination status.

Characteristic		Total	Vaccinated	Not Vaccinated	p-value
			(row %)
		N=1510	N=294	N=1216
Influenza-positive	No	1359	276 (20%)	1083 (80%)	0.01
	Yes	151	18 (12%)	133 (88%)
Influenza Season	Early	572	98 (17%)	474 (83%)	0.06
	Middle	485	92 (19%)	393 (81%)
	Late	453	104 (23%)	349 (77%)
Age Group	0 months	399	96 (24%)	303 (76%)	<0.001
	1 month	507	92 (18%)	415 (82%)
	2–3 months	411	88 (21%)	323 (79%)
	4–5 months	193	18 (9%)	175 (91%)
Gender	Female	664	123 (19%)	541 (81%)	0.41
	Male	846	171 (20%)	675 (80%)
Study Site	Nashville	554	84 (15%)	470 (85%)	<0.001
	Rochester	425	142 (33%)	283 (67%)
	Cincinnati	531	68 (13%)	463 (87%)
Study Year	2002–2003	99	18 (18%)	81 (82%)	<0.001
	2003–2004	251	25 (10%)	226 (90%)
	2004–2005	322	43 (13%)	279 (87%)
	2005–2006	176	31 (18%)	145 (82%)
	2006–2007	230	45 (20%)	185 (80%)
	2007–2008	232	57 (25%)	175 (75%)
	2008–2009	200	75 (38%)	125 (63%)
Race-ethnicity	White	698	147 (21%)	551 (79%)	0.005
	Black	430	63 (15%)	367 (85%)
	Hispanic	363	80 (22%)	283 (78%)
Medical covariates
Premature	Yes	178	33 (19%)	145 (81%)	0.73
	No	1325	260 (20%)	1065 (80%)
High Risk Condition	Yes	119	22 (18%)	97 (82%)	0.78
	No	1391	272 (20%)	1119 (80%)
Social covariates
Exposed to Smoke	Yes	613	83 (14%)	530 (86%)	<0.001
	No	896	211 (24%)	685 (76%)
# of Siblings	0	341	75 (22%)	266 (78%)	0.32
	1	539	108 (20%)	431 (80%)
	2	341	64 (19%)	277(81%)
	3+	289	47 (16%)	242 (84%)
Daycare	Yes	152	29 (19%)	123 (81%)	0.89
	No	1356	265 (20%)	1091 (80%)
Insurance	Public	891	146 (16%)	745 (84%)	<0.001
	Private	507	137 (27%)	370 (73%)
	None	105	8 (8%)	97 (92%)
Ever Breastfed	Yes	916	207 (22%)	709 (77%)	<0.001
	No	594	87 (15%)	507 (85%)

Percentages may not sum to 100% due to rounding.