Parental refusal of varicella vaccination and the associated risk of varicella infection in children.
ABSTRACT To quantify both the individual-level and attributable risk of varicella infection requiring medical care in children whose parents refuse varicella immunizations.
Matched case-control study with conditional logistic regression analysis.
Kaiser Permanente of Colorado (KPCO) health plan between 1998 and 2008.
Each pediatric physician-diagnosed case of varicella (n = 133) was matched to 4 randomly selected controls (n = 493). Cases were matched by age, sex, and length of enrollment in KPCO. Main Exposures Varicella vaccine refusal.
There were 7 varicella vaccine refusers (5%) among the cases and 3 (0.6%) among the controls. Children of parents who refused varicella immunizations were at a greatly increased risk of varicella infection requiring medical care (odds ratio, 8.6; 95% confidence interval, 2.2-33.3) compared with children of parents who accepted vaccinations (P = .004). In the entire KPCO pediatric population, 5% of varicella cases were attributed to parental vaccine refusal.
Children of parents who refuse varicella immunizations are at high risk of varicella infection relative to vaccinated children. These results will be helpful to health care providers and parents when making decisions about immunizing children.
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ABSTRACT: We summarized studies describing the prevalence of, trends in, and correlates of nonmedical exemptions from school vaccination mandates and the association of these policies with the incidence of vaccine-preventable disease. We searched 4 electronic databases for empirical studies published from 1997 to 2013 to capture exemption dynamics and qualitatively abstracted and synthesized the results. Findings from 42 studies suggest that exemption rates are increasing and occur in clusters; most exemptors questioned vaccine safety, although some exempted out of convenience. Easier state-level exemption procedures increase exemption rates and both individual and community disease risk. State laws influence exemption rates, but policy implementation, exemptors' vaccination status, and underlying mechanisms of geographical clustering need to be examined further to tailor specific interventions. (Am J Public Health. Published online ahead of print September 11, 2014: e1-e23. doi:10.2105/AJPH.2014.302190).American Journal of Public Health 09/2014; 104(11):e1-e23. DOI:10.2105/AJPH.2014.302190 · 4.23 Impact Factor
Pediatrics 08/2014; 134(3). DOI:10.1542/peds.2014-1883 · 5.30 Impact Factor
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ABSTRACT: 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. 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, Clinical Modification codes). We identified 5 statistically significant clusters of underimmunization among children who turned 36 months old during 2010-2012. The underimmunization rate within clusters ranged from 18% to 23%, and the rate outside them was 11%. Children in the most statistically significant cluster had 1.58 (P < .001) times the rate of underimmunization as others. Underimmunization with measles, mumps, rubella vaccine and varicella vaccines clustered in similar geographic areas. Vaccine refusal also clustered, with rates of 5.5% to 13.5% within clusters, compared with 2.6% outside them. Underimmunization and vaccine refusal cluster geographically. Spatial scan statistics may be a useful tool to identify locations with challenges to achieving high immunization rates, which deserve focused intervention. Copyright © 2015 by the American Academy of Pediatrics.