Description
While measles vaccination rates remain relatively high in the United States, outbreaks of the virus still occur annually. 2011 saw the highest number of cases (222) in the United States in almost 15 years, and 2012 was just as high (223 cases); inadequate or nonexistent vaccination of children against measles contributed significantly to the outbreaks resulting in many of these cases. This study attempts to assess what demographic factors might be associated with a child being not up-to-date on their recommended measles-containing vaccine (MCV), using the 2011 National Immunization Survey (NIS) dataset. The dataset was comprised of the results of a national telephone survey of households with children between the ages of 19 and 35 months, as well as the physician-provided immunization details for the most children included. Of an original sample size of 27,305, n = 18,516 with full physician records and no non-imputed missing values of the independent variables were used in this study. The data was weighted, in order to reduce the bias involved in the differential between the families for whom physician data was available and those for whom it was not. The independent variables examined were maternal education level, maternal age, family's poverty/income status, child's race/ethnicity, geographic census region, child's firstborn status, maternal marital status, and child's sex. 1,414 (7.53%) of the sampled children were not up to date on their MCV coverage. Almost two-thirds of the sample had currently married mothers (63.40%), and the largest racial/ethnic category was white, with 49.05% of the sample. A multiple logistic regression was performed on the weighted data to assess the relationship between measles vaccine up-to-date status and the independent variables. Census region, race/ethnicity by firstborn status interaction, and maternal age group by poverty status interaction were found to be significantly associated with MCV up-to-date status. Using the West as the reference value for census region, children from the Midwest (marginally) and South had significantly lower odds of being not up-to-date on their MCV, with an odds ratio of 0.74 (95% CI: 0.55, 0.995) for the Midwest and 0.68 (95% CI: 0.50, 0.87) for the South. Compared to non-firstborn children (the reference category), firstborn children have lower odds of being not up-to-date on their MCV across all racial groups. This difference is most significant among children in the multiple/other race/ethnicity category (with OR = 0.24) and least significant among Hispanic children (OR = 0.88). Children of families that were above the poverty limit but made less than $75,000 a year with mothers under the age of 20 had 1.4 times greater odds of being not up-to-date than their counterparts in families below the poverty line. Children of families with incomes exceeding $75,000 and mothers between the ages of 20 and 29 had much lower odds of being not up-to-date (OR = 0.58). All analyses and results are attributable to the author and not to the National Center for Health Statistics, which is responsible only for the initial data.
