Childhood vaccination is considered one of the top public health accomplishments of the 20th century [1].

Nevertheless, nationally, the proportion of children age 19 to 35 months who were up-to-date with all recommended vaccines in 2014 was 72%, well below the Centers for Disease Control and Prevention’s (CDC’s) Healthy People 2020 target of 90%, with lowest coverage for diphtheria, tetanus, and acellular pertussis; Haemophilus influenza type b, and the pneumococcal conjugate vaccine [2]. Meanwhile, increasing proportions of pediatricians are reporting that they have encountered patients whose parents refuse vaccines, and that they dismiss families from their practices due to vaccine refusal [3].

There is some evidence that children whose parents have negative views about vaccine safety or efficacy (e.g. mistaken concerns about autism) are less likely than other children to be sufficiently vaccinated [4,5]. However, in the U.S. population as a whole, lack of economic resources and lack of geographic proximity to pediatricians are also associated with insufficient vaccination coverage. Although vaccine refusal is a growing concern among providers, its contribution to under-vaccination, in comparison to issues of access and consistency of care, is unknown [2,6,3].

HealthCore wanted to better understand the recent trends in early childhood vaccination rates as well as reasons for incomplete vaccination. In partnership with Blue Cross Blue Shield Association, we examined early childhood vaccination trends for U.S. commercially insured children. We analyzed claims data for children in four birth cohorts (those born in 2010, 2011, 2012 and 2013) and followed their care continuously from birth through 3 years of age. Our study focused on completion rates of the Centers for Disease Control and Prevention’s recommended seven-vaccine series for children between the years 2013 (by which time the vaccines should have been completed for the first birth cohort) and 2016.

On a positive note, we found a steady increase in childhood vaccination rates over time – 77 percent of children born in 2013 completed their CDC-recommended seven-vaccine series by 2016, up from 69 percent for children born in 2010 and completing the seven-vaccine series by 2013. The individual rates for each vaccine in this series also increased during this period, with all vaccines reaching 80 percent by 2016. More concerning was the fact that, despite these improvements, some of these vaccines remain below the CDC and World Health Organization optimum levels to ensure herd immunity in the population, including vaccines for diphtheria, pertussis and measles.

Also concerning was the wide geographic variation in vaccine rates across the country. For example, in 2016, the seven-vaccine series completion rates by state for children in the 2013 birth cohort ranged from a high of 86 percent in North Dakota to a low of 63 percent in Nevada.

When we analyzed potential reasons for under-vaccination we found that documented parental/guardian refusals increased nearly 70 percent for children born in 2013 compared to children born in 2010 (4.2 percent versus 2.5 percent of each cohort, respectively). However, failure to attend routine well-child visits was the predominant reason for under vaccination among commercially insured children. Missed well-child visits were identified as the reason for under vaccination 62 percent of the time among children who did not complete their vaccination regimens in 2016. Among these same under-vaccinated children, documented parental/guardian refusal was identified six percent of the time.

What do these findings mean?

We should be worried about increasing parental refusal to vaccinate but more importantly we need to get the babies and toddlers to the doctor’s office first so the conversations about benefits of early childhood vaccination can occur between parents and their children’s doctor.

[1] Centers for Disease Control and Prevention. Ten Great Public Health Achievements – United States, 2001-2010. Morbidity and Mortality Weekly Report. 2011;60(19).

[2] Hill HA, Elam-Evans LD, Yankey D, Singleton JA, Kolasa M. National, State, and Selected Local Area Vaccination Coverage Among Children Aged 19-35 Months – United States, 2014. Morbidity and Mortality Weekly Report. 2015;64(33).

[3] Hough-Telford C, Kimberlin DW, Aban I, Hitchcock WP, Almquist J, Kratz R, et al. Vaccine Delays, Refusals, and Patient Dismissals: A Survey of Pediatricians. Pediatrics. 2016.

[4] Smith PJ, Humiston SG, Parnell T, Vannice KS, Salmon DA. The Association Between Intentional Delay of Vaccine Administration and Timely Childhood Vaccination Coverage. Public Health Reports. 2010;125.

[5] Smith PJ, Marcuse EK, Seward JR, Zhao Z, Orenstein WA. Children and Adolescents Unvaccinated Against Measles: Geographic Clustering, Parents’ Beliefs, and Missed Opportunities. Public Health Reports. 2015;130(5):485-504.

[6] Smith PJ, Singleton JA. County-Level Trends in Vaccination Coverage Among Children Aged 19-35 Months – United States, 1995-2008. Morbidity and Mortality Weekly Report. 2011;60(4).