# **Background**

On December 8, 2020, the first COVID-19 vaccine outside a clinical trial was administered. **[1]** Two years onwards, the COVID-19 vaccine drive has become the largest vaccination effort in history and has reached over 5.4 billion people globally. **[2, 3]** Challenges for COVID-19 vaccination campaigns differ from past vaccination efforts. Instead of taking years or even decades of development, the first COVID-19 vaccines achieved emergency approval within less than a year of the first recorded cases of the disease. **[4, 5]** Such rapid development has given rise to concerns among members of the public regarding the safety of COVID-19 vaccines and has led to additional scrutiny. **[6]** Following the availability of COVID-19 vaccines, the severity of the pandemic that ensued over the course of 2020 has also put time pressure on the rollout of vaccination campaigns, has led to supply shortages and resulted in vastly heterogeneous availability of COVID-19 vaccines across the globe. **[7]** Consequently, many low- and middle-income countries that lack the ability to produce vaccines of their own have relied on donations of vaccine doses from vaccine-producing countries and face infrastructural challenges in the rollout of their vaccination campaigns. Some of these challenges have still not been completely overcome 2 years after. **[8]** A region that has been of particular concern in the quest for global COVID-19 vaccine coverage has been Sub-Saharan Africa. Sub-Saharan Africa is the world’s poorest region. Here, capacity to develop or procure COVID-19 vaccines is lowest and structural barriers that complicate vaccine delivery are pervasive. As a result, COVID-19 vaccine coverage in Sub-Saharan Africa is trailing other regions. **[9]** Furthermore, SubSaharan Africa is a data-scarce environment with typically little robust information on issues such as vaccine acceptance or barriers of access that can inform the rollout of vaccination campaigns. Yet, SubSaharan Africa is home to over 1.16 billion people, about 15% of the world’s population. This makes it a systemically important region in the global effort to contain COVID-19 and end the pandemic.

The special status of COVID-19 vaccination campaigns in Sub-Saharan Africa has created the need for research to fill knowledge gaps around the effective mass delivery of COVID-19 vaccinations in the region. **[8–12]** In an effort to fill this gap, the World Bank supported a series of cross-country comparable high-frequency phone surveys (HFPS) in early 2020 that collect recurring information on vaccine hesitancy, uptake, barriers of access and information transmission in the context of COVID-19 vaccines in SubSaharan Africa.

In this paper, we bring together two years of data and findings from the HFPS across five Sub-Saharan African countries. We focus on COVID-19 vaccine acceptance as a prerequisite for widespread vaccine coverage in the region and a matter of particular concern given the special circumstances of COVID-19 vaccine development. COVID-19 vaccine hesitancy has been the subject of a number of studies across lowand middle-income countries, including in Sub-Saharan Africa, however, there is a lack of longitudinal evidence. **[9–11, 13–17]** Such longitudinal evidence is needed to understand the dynamics of vaccine acceptance in the region with some of the world’s lowest COVID-19 vaccine coverage figures. By virtue of the recurring nature of the HFPS, we are able to study vaccine attitudes and their correlates at the countrylevel and among a panel of individuals over a 2-year time horizon.

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