Table 2.

Influenza Vaccination Rates During Baseline (July 2010–February 2011), Active Intervention (July 2011–February 2012), and Maintenance (July 2012–February 2013) Years

Site	Baseline Overall (n = 35,534)		Active Intervention Overall (n =42,168)		Maintenance Overall (n = 44,923)		Immediate Intervention Effect	Overall (2 Year) Intervention Effect	Sustained Intervention Effect
	No. of Patients	Percentage Vaccinated (Column a)	No. of Patients	Percentage Vaccinated (Column b)	No. of Patients	Percentage Vaccinated (Column c)	Difference, % (b – a)	Difference, % (c – a)	Difference, % (c – b)
1	537	14.0	603	26.0	478	24.7	12.1*	10.7*	−1.4
2	1357	24.2	1370	43.0	1305	39.9	18.8*	15.8*	−3.0
3	523	28.5	1735	48.2	1885	45.5	19.8*	17.0*	−2.8
4	2009	36.8	6787	65.2	7037	62.1	28.4*	25.4*	−3.0†
5	5913	42.3	5815	52.9	6013	55.1	10.7*	12.9*	2.2**
6	3886	42.1	4174	54.9	4658	56.9	12.8*	14.8*	2.0
7	3959	49.9	4138	60.9	4637	62.8	11.0*	12.9*	1.9
8	7189	54.0	7346	61.1	7745	65.4	7.0*	11.3*	4.3†
9	6047	63.2	5866	64.4	6214	67.0	1.2	3.8*	2.6*
10	4114	67.4	4334	69.3	4951	70.3	1.9	2.9*	1.0
Site average		42.2		54.6		54.9	12.4*	12.7†	0.3
All children combined		50.3		59.7		61.1	9.4*	10.8†	1.4

^*P < .01 for difference in vaccination rates between seasons by paired t tests for within-site comparisons and by t tests for overall comparison.

^**P < .05 for difference in vaccination rates between seasons by paired t tests for within-site comparisons.

^†P < .001 for difference in vaccination rates between seasons by paired t tests for within-site comparisons and by t tests for overall comparison.