**Recovering from the Unprecedented Backsliding in Immunization Coverage: Learnings from Country Programming in Five Countries through the Past Two Years of COVID-19 Pandemic Disruptions**

**Anithasree Athiyaman \*, Tosin Ajayi \*, Faith Mutuku, Fredrick Luwaga, Sarah Bryer, Omotayo Giwa, Shadrack Mngemane, Nnang Nadege Edwige and Leslie Berman**

> Clinton Health Access Initiative (CHAI), Global Vaccines Delivery Team and Country Offices, Boston, MA 02127, USA

**\*** Correspondence: aathiyaman@clintonhealthaccess.org (A.A.); tajayi@clintonhealthaccess.org (T.A.)

**Abstract:** Between 2020 and 2021, the COVID-19 pandemic severely strained health systems across countries, leaving millions without access to essential healthcare services. Immunization programs experienced a 'double burden' of challenges: initial pandemic-related lockdowns disrupted access to routine immunization services, while subsequent COVID-19 vaccination efforts shifted often limited resources away from routine services. The latest World Health Organization (WHO) and United Nations Children's Fund (UNICEF) estimates suggest that 25 million children did not receive routine vaccinations in 2021, six million more than in 2019 and the highest number witnessed in nearly two decades. Recovering from this sobering setback requires a united push on several fronts. Intensifying the catch-up of routine immunization services is critical to reach children left behind during the pandemic and bridge large immunity gaps in countries. At the same time, we must strengthen the resilience of immunization systems to withstand future pandemics if we hope to achieve the goals of Immunization Agenda 2030 to ensure vaccinations are available for everyone, everywhere by 2030. In this article, leveraging the key actions for sustainable global immunization progress as a framework, we spotlight examples of strategies used by five countries—Cambodia, Cameroon, Kenya, Nigeria, and Uganda—who have exhibited exemplar performance in strengthening routine immunization programs and restored lost coverage levels in the last two years of the COVID-19 pandemic. The contents of this article will be helpful for countries seeking to maintain, restore, and strengthen their immunization services and catch up missed children in the context of pandemic recovery and to direct their focus toward building back a better resilience of their immunization systems to respond more rapidly and effectively, despite new and emerging challenges.

**Keywords:** routine immunization; COVID-19 pandemic; coverage backsliding; recovery; Cambodia; Cameroon; Kenya; Nigeria; Uganda
