# **1. Introduction**

High vaccination rates are widely considered an essential component in managing the COVID-19 pandemic. Initially, a major constraint was a lack of supply of vaccines, especially in low- and middleincome countries (Rouw et al., 2021). As vaccines started to become more readily available throughout 2021, it became clear that limited demand also posed a significant challenge in some countries, with many people unwilling to be vaccinated for COVID-19 even when provided the opportunity (Africa CDC, 2021; Solís Arce et al., 2021). Many low- and middle-income countries that received COVID-19 vaccines through the global COVAX facility were unable to fully disperse their first batch of vaccines before they expired. In addition to structural barriers and limitations of the health system, a key reason for the lack of use of COVID-19 vaccines was hesitancy among eligible populations (Mwai, 2021). This raises the question as to what governments could be doing to address people’s hesitancy about receiving a COVID19 vaccine in these settings.

In this paper we report on the findings of research studying drivers of vaccine hesitancy as well as research on ways of increasing people’s willingness to get a COVID-19 vaccine. Our data comes from a combination of a broadly representative phone survey and an online randomized survey experiment in Papua New Guinea (PNG). PNG is an ideal setting to examine this issue as COVID-19 vaccination rates are among the lowest in the world (Howes, 2021); existing evidence suggests there are extremely high levels of vaccine hesitancy (Fox, 2021; Pogo et al., 2021) and this issue is viewed by many commentators as the binding constraint on the country’s pathway out of the pandemic (Howes, 2021). The phone survey used in this paper covered over 2,500 households and was conducted in May and early June 2021. The survey included questions about people’s willingness to get a COVID-19 vaccine and the factors that could be contributing to this, such as beliefs about the behavior of others and people’s most trusted sources of information about the vaccine. The results were weighted to match the general population based on the most recent nationally representative survey that included a measure of household welfare, which is the 2016–18 Demographic and Health Survey (DHS). The online randomized survey experiment was conducted in late June and throughout July 2021 with around 2,400 participants and trialed whether messages informed by the findings of the phone surveys could reduce people’s hesitancy about getting the COVID-19 vaccine. Specifically, the treatments that were tested referred to expert advice, social norms and the relative safety of the vaccine.

There is wide-ranging research about the potential drivers of vaccine hesitancy in general and existing work highlights that people’s beliefs, along with social norms, often play a crucial role in determining their willingness to get vaccinated (for reviews of existing work see: Brewer et al., 2017; Dubé et al., 2015; Larson et al., 2014). For example, people’s beliefs about the effectiveness of a vaccine in preventing illness (compared to the risk of negative side effects) and their own concerns about being infected are expected to influence whether they are willing to get vaccinated. Similarly, prior studies have shown that vaccine hesitancy appears to be related to the behavior of others and people’s most trusted information sources, particularly whether people trust misinformation on social media (Africa CDC, 2021; Ahearn, 2021). In addition, some evidence shows that a relationship exists between previously being vaccinated for another disease (which suggests having trusted a vaccine at some point in the past) and willingness to get a newly developed vaccine (Brewer et al., 2017). The vaccine hesitancy literature includes mixed effects of determinants such as socioeconomic status and education, which have different relationships to hesitancy depending on country and other contextual factors 2