<p><strong>OBJECTIVES: </strong>To assess the relationship between vaccination status and clinician adherence to quality measures for children with acute respiratory tract illnesses.</p>

<p><strong>METHODS: </strong>We conducted a multicenter prospective cohort study of children aged 0 to 16 years who presented with 1 of 4 acute respiratory tract illness diagnoses (community-acquired pneumonia, croup, asthma, and bronchiolitis) between July 2014 and June 2016. The predictor variable was provider-documented up-to-date (UTD) vaccination status. Our primary outcome was clinician adherence to quality measures by using the validated Pediatric Respiratory Illness Measurement System (PRIMES). Across all conditions, we examined overall PRIMES composite scores and overuse (including indicators for care that should not be provided, eg, C-reactive protein testing in community-acquired pneumonia) and underuse (including indicators for care that should be provided, eg, dexamethasone in croup) composite subscores. We examined differences in length of stay, costs, and readmissions by vaccination status using adjusted linear and logistic regression models.</p>

<p><strong>RESULTS: </strong>Of the 2302 participants included in the analysis, 92% were documented as UTD. The adjusted mean difference in overall PRIMES scores by UTD status was not significant (adjusted mean difference -0.3; 95% confidence interval: -1.9 to 1.3), whereas the adjusted mean difference was significant for both overuse (-4.6; 95% confidence interval: -7.5 to -1.6) and underuse (2.8; 95% confidence interval: 0.9 to 4.8) composite subscores. There were no significant adjusted differences in mean length of stay, cost, and readmissions by vaccination status.</p>

<p><strong>CONCLUSIONS: </strong>We identified lower adherence to overuse quality indicators and higher adherence to underuse quality indicators for children not UTD, which suggests that clinicians "do more" for hospitalized children who are not UTD.</p>