Table 3.

Comparison of average differences in influenza vaccination across sites from pre-intervention to intervention

Group	Intervention arm		Control arm
	Cluster vaccination increase, M (SD)	p-value* for difference within Intervention arm	Cluster vaccination increase, M (SD)	p-value* for difference within Control arm	p-value† for difference between Intervention and Control arms
Overall	9.9 (6.6)	0.001	4.2 (4.2)	0.012	0.007
Age group
6–23 months	7.2 (8.8)	0.028	5.2 (7.5)	0.057	0.586
2–8 years	10.2 (7.6)	0.002	3.6 (6.8)	0.126	0.057
9–18 years	11.1 (7.4)	0.001	4.3 (4.4)	0.012	0.024
Race
Non-white	16.7 (7.2)	<0.001	4.6 (4.7)	0.013	<0.001
White	8.1 (5.8)	0.002	3.7 (4.0)	0.018	0.063

Note: Differences from pre-intervention (2010–2011) to intervention (2011–2012) years were calculated for each site (cluster), then averaged for each intervention arm (Intervention and Control). Boldface indicates statistical significance.

^*By Paired t-tests.

^†By t-test.