**5. Limitations**

This evaluation had several limitations, including the method of convenience sampling in the exit interviews and FGDs, as well as the small size of the clinics' catchment populations, which impacted our ability to make inferences about caregivers who were not utilizing the clinics with the exit interview data. To overcome these limitations, we sought to increase the richness of the data by integrating our qualitative and quantitative findings. Additionally, exit interviews are subject to response bias, which can shift responses toward positive feedback. We also relied on administrative records to monitor changes in immunization doses administered over time, which may subject those results to the limitations of written and improvised records in low-resource settings [29]. Finally, while the results provide initial evidence about the success of container clinics in improving urban access to immunization, they are not generalizable to other urban settings in Ghana. We suggest that the lessons learned from this initial implementation inform future scale-up and full impact evaluations of container clinics as an urban immunization strategy.

#### **6. Conclusions**

Our initial data support that container clinics were an acceptable method for delivering immunization services to urban populations, at least in the short term. Our findings also highlight the importance of community engagement and context-tailored strategies to improve urban access to immunization; container clinics may be a more acceptable strategy when designed to serve working mothers and built-in strategic areas (e.g., urban markets). Further studies to understand the potential role of container clinics as an urban immunization strategy are needed, including studies on their cost-effectiveness, long-term sustainability, impact on immunization coverage, and ability to expand services to meet other community needs.

**Author Contributions:** Conceptualization, A.S., M.T.W., K.A.-A., R.A., J.O., D.B., P.Q., F.O.-S., F.A., G.B. and L.C.; formal analysis, A.S., M.T.W., R.A. and D.B.; methodology, A.S., M.T.W., R.A., A.S.W., D.B. and L.C.; project administration, M.T.W., K.A.-A., J.O., P.Q., F.O.-S., F.A. and G.B.; supervision, K.A.-A., J.O., A.S.W., P.Q., F.O.-S., F.A. and G.B.; writing—Original draft, A.S., M.T.W., R.A., A.S.W., D.B. and L.C.; writing—Review and editing, A.S., M.T.W., K.A.-A., R.A., J.O., A.S.W., D.B., P.Q., F.O.-S., F.A., G.B. and L.C. All authors have read and agreed to the published version of the manuscript.

**Funding:** Global Health Security Agenda funded the Centers for Disease Control and Prevention Immunization Second Year of Life project.

**Institutional Review Board Statement:** This work was determined to be a non-research evaluation by CDC.

**Informed Consent Statement:** Informed consent was obtained from all persons involved in the evaluation.

**Data Availability Statement:** The datasets used and/or analyzed during the current project may be available upon reasonable request.

**Acknowledgments:** We would like to thank Mawuli Nyaku and Neetu Abad, the Ghana Field Epidemiology and Laboratory Training Program, the nurses at the container clinics, and the Accra Metropolitan Health Authorities for their contributions to this evaluation.

**Conflicts of Interest:** The authors declare no conflict of interest. The findings and conclusions in this report are those of the authors and do not necessarily represent the views of the Centers for Disease Control and Prevention.
