[DUPLICATE] Geographic Clusters in Underimmunization and Vaccine Refusal.

BACKGROUND AND OBJECTIVE: Parental refusal and delay of childhood

vaccines has increased in recent years and is believed to cluster

in some communities. Such clusters could pose public health risks

and barriers to achieving immunization quality benchmarks. Our aims

were to (1) describe geographic clusters of underimmunization and

vaccine refusal- (2) compare clusters of underimmunization with

different vaccines- and (3) evaluate whether vaccine refusal

clusters may pose barriers to achieving high immunization rates.

METHODS: We analyzed electronic health records among children born

between 2000 and 2011 with membership in Kaiser Permanente Northern

California. The study population included 154 424 children in 13

counties with continuous membership from birth to 36 months of age.

We used spatial scan statistics to identify clusters of

underimmunization (having missed 1 or more vaccines by 36 months of

age) and vaccine refusal (based on International Classification of

Diseases- Ninth Revision- Cl