**5. Conclusions**

This study presented a practical scenario in Cameroon, where national data masked the impact of the COVID-19 pandemic on childhood immunization in COVID-19 hotspot regions. Indeed, the study revealed a remarkable decrease in vaccination access and utilization in the two COVID-19 hotspot regions, with an increase in DTP-series dropout rate during the pandemic compared to the pre-pandemic period. Therefore, there is a resounding need to develop and implement recovery and catch-up immunization strategies to mitigate the impact of the pandemic on routine childhood immunization in these regions. To ensure the continuity of childhood routine immunization in future pandemics, there is need to set up a system that will drive the early detection of the impact of the pandemic on immunization services. Moreover, a digital tool that would evaluate the impact of the pandemic at all operational levels in real-time will be of great value. This will help unveil the pandemic's true impact and support data-driven decision making. Additionally, the study findings can be leveraged to inform policies on sustaining immunization services during future pandemics in Cameroon.

**Author Contributions:** Conceptualization, Y.S., P.D.M., S.C.N., E.M. and S.A.C.C.; data curation, Y.S. and S.C.N.; formal analysis, Y.S. and S.C.N.; funding acquisition, Y.S. and P.D.M.; investigation, Y.S.; methodology, Y.S., P.D.M., S.C.N., E.M. and S.A.C.C.; project administration, Y.S.; supervision, P.D.M., C.S.Z., E.M. and S.A.C.C.; validation, Y.S.; writing—original draft, Y.S. and S.C.N.; writing—review and editing, Y.S., P.D.M., S.C.N., N.N.E., B.N., S.T.N., R.A., C.S.Z., A.A.N., A.A., N.J.M., O.W., S.N. and E.M. All authors have read and agreed to the published version of the manuscript.

**Funding:** This research received no external funding.

**Informed Consent Statement:** This study did not involve individual-level data, so ethical clearance was not required.

**Data Availability Statement:** Data from the corresponding author of this research is available upon reasonable request. However, the Cameroon DHIS-2 databased was used as the data source.

**Acknowledgments:** This study was nested in a project that was funded by Gavi, the Vaccine Alliance. We are grateful to this institution for its generous financial support to Clinton Health Access Initiative, Inc., for the realization of this and other similar projects. It is important to highlight that while acknowledging the support of these institution, the institutions had not role in deciding whether or not to publish these data. As a result, the content of the paper is purely the responsibly of the authors. We would also like to thank the staff of Cameroon's Expanded Program on Immunization for sharing field observations that inspired this study.

**Conflicts of Interest:** The authors declare no conflict of interest.

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