PC2189: Worth a Shot: Quality Improvement Efforts to Monitor and Increase Routine Childhood Immunization Catch-up Rates Across the Military Health System During the COVID-19 Pandemic

Purpose/Objectives: During the COVID-19 pandemic, routine childhood immunization rates fell across the United States; the Military Health System (MHS) was no exception. Immunization rates in the MHS decreased from 85-95% to 70-80% across the geographically-dispersed MHS. This poses a public health concern since a population’s immunization rate determines the risk of transmission of vaccine-preventable diseases. For measles, that rate is >92%.

Design/Methods: We sought to identify children missing routine childhood immunizations and implement countermeasures to increase immunization rates to pre-pandemic levels. Due to immunization schedule complexity, MMR immunization rates served as proxy outcome measures for routine immunization rates. Medical record extracts informed the MHS Population Health Portal (MHSPHP) and the percentage of 16-18 month olds and 6 year olds who had received MMR #1 and MMR #2, respectively. A run chart tracked percentages monthly from August 2021 in the MHS and by geographic markets. Weighted standard deviations determined variation by market. Multiple countermeasures aimed to increase immunization rates. The Defense Health Agency issued a memo MHS-wide directing the catch-up effort and providing central resources (phone scripts to use when contacting families, immunization registry shortcuts, training for clinic personnel). Subsequent interventions included continued training, tagging of under-immunized children in the registry, and monthly discussions with Market Chief Medical and Nursing Officers.

Results: In August 2021, the percentage of all enrollees 16-18 months old immunized with MMR #1 vaccine was 88%; for 6 year olds, 91% had received MMR #2. By March 2022, those percentages were 84% and 91%, respectively (Figure 1, Figure 2). Measures of variation by geographic market increased from 3% to 5%; Hawaii’s enrolled 16-18 month olds had a 16% decrease in MMR #1 immunization, and San Diego experienced a 12% increase. For MMR #2, there was less variation by geographic market, with Hawaii’s 5% increase being the largest change.

Conclusion/Discussion: Childhood immunization rates with MMR vaccine remain below the rate necessary to prevent community transmission of measles in a large, universally-covered, low-to-no cost health system. The association of countermeasures with changes in immunization rates over 9 months varied by geographic market, with widening disparities in the percentage of infants immunized with MMR #1.