Report: Middle school vaccine mandates work

Mandates for middle school vaccines like Tdap decrease incidence of pertussis by more than half, and increase uptake of other vaccines less frequently required in adolescents, according to a new paper.

The Center for Disease Control and Prevention’s (CDC) Advisory Committee on Immunization Practices (ACIP) recommends that children receive vaccinations against meningococcal infections (MCV), human papillomavirus (HPV) and seasonal influenza before entering middle school, but state mandates for these vaccinations vary.

A new working paper from researchers at Vanderbilt University investigates the efficacy of school vaccination mandates. Using data from the National Immunization Survey between 2008 and 2013, the research team studied herd immunity as well as “cross-vaccine spillover”-where teens who were required to receive the Tdap vaccine opted for other recommended vaccines, as well.

Christopher Carpenter, PhD, an economics professor at Vanderbilt University who co-authored the working paper, said the goal was to investigate the efficacy of school mandates for vaccination, which have been increasingly utilized. Forty-six states now require Tdap vaccination for middle school entry. Nineteen states also require MCV, and two states require HPV vaccination.

“We find that when there is a vaccine-specific mandate, vaccination rates for Tdap and Meningococcal Conjugate are about 80%, so there seems to be substantial non-compliance,” Carpenter told Medical Economics.

He added that during the sample period, exemptions could be obtained for individuals whose religious beliefs oppose vaccination in all but two states, and 20 states additionally allowed exemptions for personal/philosophical beliefs. All states grant exemptions for children who cannot be vaccinated due to medical reasons.
Carpenter noted that researchers did not find that mandates had smaller effects in states that allowed exemptions for personal/philosophical beliefs compared to other states.

Tdap vaccination is widely required for middle school entry and is very effective, according to the paper. By 2013, 80% of incoming middle school students had received the vaccine, resulting in a 53% decline in pertussis cases. Mandates requiring the vaccine increased uptake by 29%, according to the paper.

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One vaccine can lead to another

In the 27 states were Tdap was required but MCV was not, researchers found evidence of a spillover effect, with teens who visited their physician for a Tdap vaccine appearing 2.1% to 2.9% more likely to get the MCV vaccine at the same time. Tdap vaccination also increased the likelihood of HPV vaccination initiation by 4.2% to 4.9% and HPV series completion by 2.5% to 3.3%. There was no evidence that Tdap mandates had any effect on uptake of the seasonal flu vaccine, according to the report, perhaps because flu vaccination typically begins after the start of the school year while Tdap must be administered before the school year begins.

Spillover effects were most frequent among African-American and Hispanic students, and mothers with less education were found to pursue the HPV vaccine for their children, according to the report.

Adolescents typically visit healthcare providers for injury rather than wellness, so this contributes to lower uptake of vaccines in this population, according to the report. The paper, however, found evidence that mandates increased contact with healthcare providers and parent interest in researching Tdap and other vaccines.

The message of the study, Carpenter said, is that vaccination among adolescents with the Tdap vaccine provided herd immunity in children under age 4 through herd immunity, and mandating one vaccine can increase the probability that individuals receive other, non-mandated vaccines.

“This suggests that if providers offered recommended vaccines and information about them at every encounter patient encounter, they would likely be able to improve adolescent vaccination rates overall,” Carpenter said.

While the authors are not making recommendations for clinical practice, Carpenter said he hopes it highlights the importance of the relationship between state public health requirements and opportunities for physicians to talk with parents about vaccination.

“Our results demonstrate that even in the absence of a mandate, policies designed to increase provider contact during adolescence or parental vaccine knowledge may significantly improve compliance with the recommended vaccination schedule for these individuals, although to a lesser extent than a mandate,” Carpenter said.