High income doesn't mean on-time shots

The children of mothers who have less than a high school education and a low socioeconomic status are more likely to be up to date with their immunizations than those whose moms are more educated and earn more money, according to a study in the February American Journal of Public Health.

"Less-educated mothers and poor mothers from certain minority groups ... can be diligent in ensuring that their children receive the recommended immunizations," said Patrick Rivers, PhD, one of the study's authors and an associate professor at Southern Illinois University.

Researchers analyzed data on 11,860 children included in the 2003 National Immunization Survey and found that children of poor African-American mothers were 74% more likely to be up to date with shots than were children from wealthier families. Women with less than a high school education were 16% more likely to have fully immunized children than were women with a college degree.

Data from the 2003 survey, as well as subsequent ones, indicate that nearly all children do eventually receive recommended vaccinations. According to the 2005 survey released by the Centers for Disease Control and Prevention in September 2006, vaccination rates hit new highs, and racial and ethnic disparities seemed to have disappeared. Still, immunization activists are concerned about disparities because it means that some children will be unprotected longer than others.

"Every day that they spend undervaccinated is another day at risk," said Lance Rodewald, MD, director of the Immunization Services Division in the CDC's National Center for Immunization and Respiratory Diseases. "We need to keep our programs as strong as possible, reach out and address the barriers for vaccination."

The issue of why parents are not keeping up with the schedule was not explored by the paper, although experts speculate that poorer women may be getting more of their children's health care from the public sector, which may have more infrastructure to support on-time vaccinations.

"This study may be documenting the impact of some different federal programs such as Medicaid and SCHIP," said Jennie J. Kronenfeld, PhD, senior author and a professor in the School of Social and Family Dynamics at Arizona State University.

Others theorize that Latinos, who may be recent immigrants from countries with a more immediate history of the diseases that vaccines protect against, may feel a more urgent call to ensure their kids get their shots. "There may be more motivation to see their children protected against these diseases," said Samuel Katz, MD, the Wilburt Cornell Davison Professor and chair emeritus of the pediatrics department at Duke University Medical Center in North Carolina.

But whatever the reasons for these disparities, physicians say that the lesson in this paper is that all children are in danger of not receiving their vaccines on time.

"Most physicians think their patients ... are up to date, but this study shows it's not just inner-city kids or this or that ethnic group," said William Cosgrove, MD, a Salt Lake City pediatrician and chair of Utah's Every Child By Two Coalition. "All children are at risk of being left behind and being underprotected."