Immunization Science

Demographics of Unvaccinated Children

Three children per thousand in the United States have never received any vaccines. This study shows that the characteristics of unvaccinated children and how they differ from undervaccinated children.

The article

Children Who Have Received No Vaccines: Who Are They and Where Do They Live? Smith PJ, Chu SY, and Barker LE. Pediatrics 2004;114(1):187-195

Explanatory note: Immunizations have prevented vaccine-preventable diseases so effectively that fear of these diseases has diminished, leading some to question the need for vaccines. Loss of fear of most of these infections is inappropriate, however, as the risks for exposure persist. As a consequence of these phenomena, concerns about vaccine safety have increased, largely fueled by misinformation about vaccine safety.

For example, some have concerns about autism and measles-mumps-rubella (MMR) vaccine, multiple sclerosis and hepatitis B vaccine, and sudden infant death syndrome and diphtheria-tetanus-pertussis (DTP) vaccine despite the fact that current scientific evidence does not support associations between these vaccines and conditions.

The question

What are the characteristics of children who have received no vaccinations compared with those who are undervaccinated and to those who are fully immunized?

The study

The National Immunization Survey (NIS) is an annual telephone survey conducted by the Centers for Disease Control and Prevention to determine the immunizations that children 19-35 months of age have received. This study used data collected in the 2001 NIS to compare characteristics of the three groups of children, their mothers, and their race and family income.

The researchers also evaluated the relationship between parents’ concerns about vaccine safety and their children being unvaccinated.

Finally, using the same data collected in previous years, they examined trends in the numbers of unimmunized children over time.

The findings

In 2001, 62.8% of US children 19 to 35 months of age were fully immunized with all the vaccines that were recommended at that time. It was estimated that 3 children per thousand had never received any vaccines (unvaccinated). The study found marked differences in the characteristics between children who were completely unvaccinated, those that either received some vaccines, and those who were fully vaccinated as recommended.

Children who had received some but not all recommended doses (undervaccinated) tended to be black and had a younger, often-unmarried mother who had less education than fully immunized children. These underimmunized children were more likely to live in a household below the poverty level, with more children, and had moved across state lines.

Compared to undervaccinated children, unvaccinated children were more likely to be non-Hispanic white, have a mother who was older, married and who had a college degree. These children were more likely to live in a household with an annual income exceeding $75,000.

Compared to fully immunized children, unvaccinated children were more likely to be non-Hispanic white and live in larger households. Educational levels, family income and other factors did not differ.

Almost half (48%) of the parents of unvaccinated children expressed a concern about vaccine safety compared to only 5% of parents of undervaccinated children. In addition, 71% of parents of unvaccinated children indicated that medical doctors have little influence over vaccination decisions for their children compared to 23% of parents of undervaccinated children.

Many children with no vaccinations lived in counties in California, Illinois, New York, Washington, Pennsylvania, Texas, Oklahoma, Colorado, Utah, and Michigan.

States that allowed philosophical exemptions to immunization laws in schools had many more unvaccinated children than states that do not have philosophical exemptions.

Between 1995 and 2000 the number of children 19-35 months who were unimmunized increased.

The relevance/bottom line

This study shows that the characteristics of unvaccinated children are very different from those of undervaccinated children. Parents of unvaccinated children are more concerned about vaccine safety than are parents whose children receive some but not all vaccines.

Unvaccinated children are concentrated in particular states, increasing the risk of transmitting vaccine-preventable diseases to other unvaccinated children, undervaccinated children and fully vaccinated children. (See Community Immunity)

NNii’s comments

Although the number of unvaccinated children is small it is increasing. Such children tend to cluster in certain states and communities raising concerns that they may be exposed to and transmit vaccine-preventable diseases within their communities and to other persons with whom they come into contact. Parents of unvaccinated children tend not to consider the advice of physicians. Underimmunized children tend to be at risk because of disparities in the economics of health care access.