Reflecting the focus of this paper, and the availability of relevant research, our literature review here is broken into two parts. First, we review the small number of descriptive, observational studies of attitudes toward COVID-19 vaccines that come from developing countries.<sup>2</sup> This literature, while small, is the most relevant for situating the findings of our observation phone survey study. Second, we review the more explicitly causal literature that attempts to explain why vaccine hesitancy exists, and whether it can be changed. Here, we do not limit our coverage either to COVID-19 or developing countries – neither have been studied enough. Rather we cast our net wider, covering vaccines for other diseases, and studies from developed countries. We use this second literature to feed into the conceptual framework used in the experimental component of our own research.

# - <u>2.1 Descriptive surveys of views on COVID 19 vaccines in developing countries</u>

The most significant published study of attitudes to COVID-19 vaccines across developing countries is that of Solís Arce et al. (2021). Their paper reports on results from surveys conducted in 13 countries, spanning the Americas, Africa, South Asia, and Europe. All countries except the Russian Federation, Colombia and the United States are low or lower-middle income countries. One clear takeaway from the study is just how much variation there is between countries in willingness to take the COVID-19 vaccine. Also striking is the fact that surveyed willingness to take the COVID-19 vaccine is higher – on average over 80 percent – in the low, and lower-middle income countries, than it is in either Russia or the United States (Solís Arce et al., 2021, p. 1389). Although results varied between countries, women tended to be somewhat less willing to be vaccinated than men, and younger respondents marginally more willing (Solís Arce et al., 2021, p. 1387).

Between-country variation in attitudes to COVID-19 vaccines is a similar standout point in another large study focused on 15 countries in Africa (Africa CDC, 2021). Stated willingness to take a COVID-19 vaccine varied from 94 percent in Ethiopia to 59 percent in the Democratic Republic of Congo (Africa CDC, 2021, p. 10). The types of people most likely to state they would be vaccinated also varied between the surveyed countries. However, older people were more likely to state they were willing to be vaccinated in most countries. In the plurality of countries differences were not clear between genders. Where differences were present it was usually the case that men were more favorably disposed to the COVID19 vaccine than women (Africa CDC, 2021, pp. 22-65).

With respect to rationales for people’s beliefs, the most common explanation for wanting the vaccine in the 13-country international study was protecting oneself from the illness. The most common reason for not wanting the vaccine was concern about side effects (Solís Arce et al., 2021, p. 1387). Concerns about vaccine safety also stood out as an issue in the Africa-focused study (Africa CDC, 2021). In addition, the Africa-focused study found that participants’ beliefs about vaccines more broadly, and whether vaccines in general were safe, were clearly correlated with their stated willingness to take a COVID-19 vaccine (Africa CDC, 2021, p. 11). This finding fits with a larger, pre-COVID global literature which found that people’s contemporary willingness to be vaccinated is strongly related to past vaccine behavior (Brewer et al., 2017, p. 165).

> 2 In addition to the work reviewed here, some ongoing COVID-19-related work is taking place at present in developing country contexts. For example see details at: <u>https://www.worldbank.org/en/events/2021/06/22/reaching-herd-immunity-behaviorally-using-social-media-insightsto-inform-covid-19-vaccination-efforts; https://www.worldbank.org/en/data/interactive/2020/11/11/covid-19-high-frequency-monitoringdashboard; and https://development-data-hub-s3-public.s3.amazonaws.com/ddhfiles/1235981/covid-whatsnew.pdf?deliveryName=DM111830.</u>

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