The magazine of the UW School of Public Health

Improving Immunization Rates in Montana

Lisa Underwood and James S. Murphy

From 2004 to 2008, Montana ranked in the lowest quintile for children 19 to 35 months of age who were up-to-date on their immunizations. This situation was a public health urgency, as low immunization rates are associated with outbreaks of vaccine-preventable diseases, disability, and rarely, death. In response, the Montana Department of Public Health and Human Services (DPHHS) Immunization Program developed a strategic approach to improve immunization rates.

State-Generated Recall Letters

The Task Force on Community Preventive Services, a non-federal and independent panel, recommends immunization reminder/recall systems as an evidence-based method for increasing immunization rates. Reminder/recall systems alert parents that their children are due (reminder) or overdue (recall) for immunizations. Before 2011, the DPHHS Immunization Program had not used an immunization reminder/recall system, instead relying on vaccine providers to remind their patients.

Children ages 19 through 23 months by December 1, 2010 enrolled in the Montana Medicaid program who were not known to have been up-to-date on the recommended immunizations were eligible for study participation. Eligibility was determined based on data from Medicaid billing records and Montana’s immunization registry, "WIZRD." Researchers reviewed 1,865 records and found that 878 children (47 percent) met the criteria. Nearly 90 percent of partcipants lived in rural or frontier counties.

Half of the study group was randomly assigned to an intervention condition in which parents received a one-time mailed letter reminding them to visit their child’s health care provider to receive the missing vaccines. The second group did not receive a recall letter. Three months after the mailing, researchers re-assessed each child’s vaccination status.

Researchers found no significant difference between study groups in the percentage of those children who received any immunizations during the three-month study period. There was also no significant difference in the proportion of children in either group who were up-to date on all immunizations at the end of the three-month period, even after excluding those with letters returned undeliverable.

This study emphasizes the importance of individual health care providers and local health departments using reminder/recall systems for rural children enrolled in Medicaid as a one-time state-generated recall letter will likely not improve immunization rates.

Enforcement of Immunization Requirements

A second strategy to increase childhood immunizations focused not on parents, but on childcare providers. In 2010, the DPHHS Immunization Program collaborated with the DPHHS Quality Assurance Division (QAD), the agency responsible for licensing Montana childcare facilities. The Administrative Rules of Montana (ARM) require all childcare facility attendees to have received certain vaccines. Prior to 2010, the administrative rules were not consistently enforced. In 2011, the DPHHS Immunization Program began requiring local health departments to increase inspection of licensed childcare facilities.

The Immunization Program, with assistance from QAD, created a memorandum of understanding (MOU) that clarified authority granted to public health nurses to review immunization records at all Montana-licensed childcare facilities. Local health officers may exclude children who do not meet the childcare facility immunization requirements. In 2011, over 600 (53 percent) of 1,139 childcare facilities were visited by public health nursing staff. These staff reviewed 16,755 immunization records. This compares with 109 facilities visited and 1,100 records reviewed for the entire year of 2009.

Ninety-two percent of immunization records reviewed by public health nurses were up-to-date per ARM compared with approximately 35 percent in 2009. This substantial increase in the percentage of childcare attendees who were up-to-date on their immunizations is likely the result of tougher enforcement by local health departments.

Medical Exemption Review Board

A child attending a childcare facility in Montana can be exempted from the required immunization(s) if, in the judgment of their treating physician, a valid medical contraindication exists. This authority is interpreted broadly, and a small number of physicians grant medical exemptions because of parents’ fear of autism, unsubstantiated allergies, and other reasons that are not based on medical evidence.

Children receiving care from these physicians often share childcare facilities. When public health nurses discover children enrolled in childcare settings who have been granted medical exemptions to immunization(s) for which the documented evidence seems insufficient, these nurses alert the State Medical Officer.

Since 2010, the State Medical Officer has received 44 medical exemptions thought to lack sufficient evidence. A review panel, formed in June 2011, advises the State Medical Officer on these medical exemptions. The panel currently consists of two family medicine physicians, two pediatricians, and two infectious disease physicians. If the review panel finds more evidence is required to justify the exemption, the State Medical Officer then sends a certified letter to the physician of record requesting the needed information. If additional information is not provided, the medical exemption is voided.

This use of the medical exemption review panel is unlikely to improve Montana’s childhood immunization rates substantially, yet the panel’s role in preventing dangerous outbreaks in facilities where groups of under-immunized children are enrolled should not be minimized.

Immunization Information System

An Immunization Information System (IIS) is a population-based electronic information system that manages immunization data. An IIS consolidates immunization-related data among multiple health care providers, generates reminder/recall notices, and assesses immunization coverage. In 2010, the Task Force on Community Preventive Services began recommending the use of these systems.

The National Vaccine Advisory Council (NVAC) recommends that a state-based IIS fulfill 12 minimum functional standards. In 2009, Montana participated in the Centers for Disease Control and Prevention Enhanced Technical Assistance Project and undertook a comprehensive review and analysis of Montana’s IIS "WIZRD." The review determined that WIZRD did not meet the 12 NVAC recommended minimum functional standards. Consequently, the DPHHS Immunization Program began the process of replacing WIZRD with a highly functional IIS called imMTrax.

DPHHS began using imMTrax as Montana’s new IIS in November 2011. The capabilities of imMTtrax include a reminder/recall system and a forecasting algorithm. The forecasting algorithm enables prediction of a child’s missing immunizations with greater accuracy. This in turn can lead to more strategic use of reminder/recall systems. Montana also received funding from CDC to work with immunization providers to exchange data electronically between the health care providers’ electronic health records and imMTrax. In the near future, the DPHHS Immunization Program will begin assessing the effect of imMTrax on Montana’s immunization rates.

Child immunization rates in Montana are low and must be improved. Since 2010, the DPHHS Immunization program has launched many initiatives to improve low immunization rates. While data supporting these initiatives are limited, preliminary data suggest small gains. It is too early to determine if strategic initiatives led to these modest improvements, but improvement is happening.


Lisa Underwood, BS, CPH, is the supervisor of the Immunization Program in the Montana Department of Public Health and Human Services (DPHHS).

James S. Murphy, BS, is the Chief of the Communicable Disease Control and Prevention Bureau in the Montana DPHHS.


Randall J. Nett, MD, MPH, Carolyn Parry, MPH, Bekki Wehner, Lori Rowe


  1. Centers for Disease Control and Prevention (CDC). Vaccine-preventable diseases: improving vaccination coverage in children, adolescents, and adults. A report on recommendations from the Task Force on Community Preventive Services. MMWR. 1999; 48(RR-8):1–15.
  2. CDC. Progress in Immunization Information Systems — United States, 2009. MMWR. 2011; 60(01):10–12.