BackgroundDuring the Fall of 2020, in the middle of the COVID-19 pandemic, the importance of avoiding a simultaneous influenza and COVID-19 “twindemic” led to the implementation of a socially distanced influenza vaccination strategy: drive through mobile vaccination clinics. Mobile clinics are a valuable resource in providing primary and preventative care to underserved populations and expanding access to healthcare to individuals who are marginalized by geographic, social, or structural barriers. Although there are about 2,000 registered mobile clinics throughout the United States and 120 reported mobile health clinics providing services in California, few studies to date evaluated the neighborhood-level factors in which those children live to determine whether social determinants of health (SDOH) influence the use of mobile drive-through clinics vs static clinics for immunizations.ObjectiveThe aims of this study were to: 1) describe the demographic and clinical distribution of pediatric patients who sought immunizations in drive-through mobile vaccination clinics compared to traditional, static clinics, and 2) determine whether the use of mobile immunization clinics were associated with social determinants of health.Designs/methodsWe conducted a retrospective cohort study of a total of 8,266 pediatric patients, 149 of whom received immunizations in 3 mobile clinics and 8,117 pediatric patients who received immunizations in 3 static clinics in Orange County from 8/1/2020 to 12/31/2020. Data were collected from patient charts on demographic characteristics (age, sex, race, ethnicity, main spoken language, insurance type) and the presence of chronic illnesses. SDOH was measured using Child Opportunity Index 2.0, a publicly available composite measure composed of 29 traditional and novel weighted indicators that captures community conditions and resources. Logistic regression will be used to examine potential associations between demographic and clinical characteristics, neighborhood level characteristics, and whether the immunization was received in a mobile or static clinic. The study was approved by our institution’s IRB.ResultsA smaller proportion of pediatric patients who were Hispanic, Spanish-speaking, and enrolled in public insurance plans received immunizations at mobile (vs static) clinics.• Less likely to obtain vaccines through mobile clinics were those who identified as:• Black (OR 0.215; 95% CI -1.60, 2.03) relative to Caucasian patients• Hispanic (0.0626; -0.00135; 0.127) relative to non-Hispanic patients• Primary language was Spanish (0.00911; -0.0356; 0.0538)• On public insurance (0.00977; - 0.00437; 0.0239) versus commercial insuranceAdditionally, those who lived in the most disadvantaged neighborhoods were the least likely to obtain vaccines at the mobile clinics (OR 0.635; 95% CI 0.619, 0.651).Conclusions:The study demonstrates that pediatric patients who lived in more disadvantaged neighborhoods were less likely to receive vaccinations at mobile clinics. Additional work is needed to identify why mobile immunization clinics were highly skewed towards those who lived in more advantaged areas.Citations• Coaston A, Lee SJ, Johnson JK, Weiss S, Hoffmann T, Stephens C. Factors associated with mobile medical clinic use: a retrospective cohort study. Int J Equity Health. 2023 Sep 26;22(1):195. doi: 10.1186/s12939-023-02004-3. PMID: 37749529; PMCID: PMC10521435.• Malone NC, Williams MM, Smith Fawzi MC, Bennet J, Hill C, Katz JN, Oriol NE. Mobile health clinics in the United States. Int J Equity Health. 2020 Mar 20;19(1):40. doi: 10.1186/s12939-020-1135-7. PMID: 32197637; PMCID: PMC7085168.• Acevedo-Garcia D, McArdle N, Hardy EF, et al. The Child Opportunity Index: improving collaboration between community development and public health. Health Aff (Millwood). 2014;33(11):1948-1957. doi:10.1377/hlthaff.2014.0679• Acevedo-Garcia D, Noelke C, McArdle N, et al. Racial and ethnic inequities in children’s neighborhoods: evidence from the new Child Opportunity Index 2.0. Health Aff (Millwood). 2020;39(10):1693-1701. doi:10.1377/hlthaff.2020.00735• Noelke C, McArdle N, Baek M, et al: Child Opportunity Index 2.0 Technical Documentation. 2020. Available at: https://www.diversitydatakids.org/sites/default/files/2020-02/ddk_coi2.0_technical_documentation_20200212.pdf. Accessed May 2, 2023