Policy Research Working Paper 10981

# **Abstract**

During the COVID-19 pandemic, low- and middle-income countries struggled with lower vaccination rates compared to wealthier countries, posing challenges to reducing virus transmission, mitigating healthcare system pressures, and promoting economic recovery. Communications campaigns offer low-cost opportunities to overcome such challenges by strengthening vaccine confidence and intentions to get vaccinated, but empirical testing is needed to identify which messages will be most effective in different contexts. To support policy-making efforts to design effective communication rapidly during the pandemic, a global research program of 28 online experiments was conducted by recruiting respondents (123,270 individuals) through social media between January 2021 and June 2022 across 23 mostly low- and middle-income countries and territories. An individual participant data (IPD) meta-analysis of these data summarizes the results of this research program testing the impact of behaviorally informed messaging on vaccine intentions. Results from the meta-analysis show that among unvaccinated survey respondents, behaviorally informed messages significantly increased the odds of vaccination intention by 1.28 times overall and up to 1.93 times in individual studies (safety messages in Papua New Guinea). Significant pooled effects of specific framings ranged from increasing the odds of vaccination intention by 1.16 times (variant framing) to 1.45 times (experts and religious leaders framing). This research underscores the importance of communication tailored to address different drivers of vaccine hesitancy and offers insights for handling future health crises with behavioral communication strategies leveraging rapid insights afforded by social media.

This paper is a product of the Development Impact Group, Development Economics. It is part of a larger effort by the World Bank to provide open access to its research and make a contribution to development policy discussions around the world. Policy Research Working Papers are also posted on the Web at http://www.worldbank.org/prwp. The authors may be contacted at dpinzonhernandez@worldbank.org, rhyslim@worldbank.org, and mdugas@worldbank.org. A verified reproducibility package for this paper is available at http://reproducibility.worldbank.org, click **here** for direct access.

<!-- Start of picture text --> TRANSPARENT<br>ANALYSIS<br>G<br>R E<br>N<br>S<br>I P<br>Y E<br>K A<br>C A<br>R P<br>LI R<br>O E<br>O C<br>W R<br>H<br>S<br>P<br><!-- End of picture text --> _The Policy Research Working Paper Series disseminates the findings of work in progress to encourage the exchange of ideas about development issues. An objective of the series is to get the findings out quickly, even if the presentations are less than fully polished. The papers carry the names of the authors and should be cited accordingly. The findings, interpretations, and conclusions expressed in this paper are entirely those of the authors. They do not necessarily represent the views of the International Bank for Reconstruction and Development/World Bank and its affiliated organizations, or those of the Executive Directors of the World Bank or the governments they represent._ Produced by the Research Support Team