TABLE 4

Spatial Clusters of MMR and VZV Underimmunization, Kaiser Permanente Northern California, 2010–2012

Vaccine Not Received by 36 Mo of Age	Cluster Number and General Description	Radius, km	Block Groups in Cluster, n	Children Missing MMR or VZV Dose, %^a	Expected Underimmunized Cases, n	Actual Underimmunized Cases, n	RR	P
MMR	1: Marin and Sonoma counties	47	517	5.6	109	177	1.69	<.001
	2: Western Contra Costa and northern Solano counties	22	435	4.9	173	245	1.49	.001
	3: Southeastern Roseville	7	175	6.6	41	78	1.96	.004
	4: Berkeley, north Oakland	3	91	8.8	14	36	2.58	.019
VZV	1: Marin, Sonoma, Napa counties	65	619	7.3	153	277	1.94	<.001
	2: San Francisco and East Bay	13	814	6.8	133	227	1.80	<.001

↵^a Outside of the MMR clusters, 3% of children did not get MMR by 36 months of age. Outside of the VZV clusters, 3.5% of children outside did not get VZV vaccine by 36 months of age.