# _4c. Limitations of this study_

One potential limitation of this study is that it is based on phone survey data which exclude respondents who did not have access to a phone. This method of data collection was necessary to collect information quickly during the early months of the COVID-19 pandemic while respecting local movement restrictions and minimizing the risk of COVID-19 transmission. Given that having a phone may be non-random, this might have created a risk that the results are representative only of the population with access to a phone. However, in the countries in this sample, access to mobile phones was high, and in countries where the sample was based on a previous survey, sampling weights were used in the analysis to correct for the biases resulting from non-random access to phones. A recent analysis using the same phone survey samples from four African countries demonstrated that the weighting procedures successfully minimized the selection bias in the phone surveys for a wide range of indicators (Ambel, Mcgee, and Tsegay 2021). Nevertheless, the variation in hesitancy estimates from different data sources, such as the phone surveys vs Facebook, also points to the need for methodological research that would explore further the biases introduced by phone surveys, or by online surveys, vis-à-vis face-to-face surveys. These types of experiments would aid the interpretation of findings in environments where data collection modalities are constrained, as was the case with the COVID-19 pandemic, and would also help guide researchers on issues related to sample corrections.

A second limitation is that country surveys were collected at different times, and some surveys were collected before a vaccine was available in the country while others were collected after the vaccine was available. During data collection (and the pandemic more generally), influential events occurred, including adverse news about side effects of certain vaccines, which could have changed respondents’ intentions. Furthermore, there are multiple vaccine manufacturers and types, and the type of vaccine available or anticipated to become available in each country may influence levels of hesitancy.

# _4d. Conclusions and policy implications_

The main findings of this paper are that on average across countries, the level of COVID-19 vaccine hesitancy is approximately 20 percent and remained unchanged in most countries between late 2020 and the first half of 2021. These results suggest that COVID-19 vaccine hesitancy in developing countries, while less prevalent than previously thought, will be an important and enduring obstacle to recovery from the pandemic. The sizeable discrepancies with other studies of COVID-19 vaccine hesitancy suggest that measures of hesitancy depend greatly on the framing of the hesitancy questions and the nature of the sample. Knowing that people over the age of 65 years are the least likely to be hesitant provides an important opportunity to scale up vaccine rollout in this population group, which is at highest risk of severe disease and mortality from COVID-19.

Although supply constraints have long been thought to be the main barrier to vaccination rollout in developing countries, these constraints have abated over time, particularly in middle- and high-income countries. Our results showed only a very small proportion of respondents reported barriers in access or lack of supply as a reason for not getting vaccinated, albeit this may be due, in part, to the framing of the questions. The most cited reasons for hesitancy were concerns about the safety of the vaccine, followed by concerns about its efficacy. At the same time, in many low-income countries, access issues remain important – the estimates in this study showed that about 20 percent of the population was hesitant to get a COVID-19 vaccine, but with only 1 in 5 individuals in low-income countries vaccinated to date, there is still a large share of the population who would get vaccinated if vaccines were made available to them, and alleviating access constraints will remain a policy priority in such contexts.

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