OBJECTIVES: In pediatric patients with sinusitis and suspected low pneumococcal antibody titers, we aimed to determine the association between a pneumococcal polysaccharide vaccine booster dose (PPSV23) and healthcare utilization. METHODS: Pediatric patients with a diagnosis of sinusitis, a PPSV23 booster dose, and pre-vaccine anti-pneumococcal antibody titers (age 2-16) were abstracted from the medical records system. Sinusitis-related healthcare encounters and antibiotic prescriptions were measured for 2 years before and after PPSV23 vaccination. A mixed effects negative binomial regression was utilized to compare pre and post-vaccine healthcare utilization while accounting for age and sex. RESULTS: A total of 233 patients were included in the study analysis. Mean age at pre-vaccination titer was 7.99 years (±3.83), 47 (20.2 %) were immunocompromised, and nearly all patients received the complete childhood pneumococcal vaccine series. When comparing pre and post-vaccination periods, encounters decreased from an average of 2.70 (95 % CI: [2.29, 3.10]) to 1.23 (95 % CI: [1.00, 1.46]). Antibiotic prescriptions decreased from 2.58 (95 % CI: [2.17, 2.98]) to 1.18 (95 % CI: [0.93, 1.42]). Mixed effects modeling demonstrated the number of encounters after vaccination decreased 51.1 % as compared to before vaccination (95 % CI: [42.9, 58.2], p <
0.002) and the number of antibiotic prescriptions decreased 51.3 % (95 % CI: [42.9 %, 58.6 %], p <
0.002). Among immunocompromised patients, encounters were decreased by 46.9 % (95 % CI: [26.2 %, 62.1 %], p <
0.002) and antibiotic prescriptions by 49.2 % (95 % CI: [28.5 %, 64.2 %], p <
0.002). CONCLUSION: PPSV23 booster vaccination was associated with a significant decrease in sinusitis-related healthcare encounters and antibiotic use among pediatric patients, including those who are immunocompromised.