Lady with a COVID-19 vaccination pass in Sierra Leone

Last mile delivery vaccine uptake in Sierra Leone

Press Release

Research published in Nature shows that mobile vaccine clinics can increase vaccine uptake amongst rural populations in developing countries, from IGC Economist and Principal Investigator, Dr Niccolo Meriggi, with Prof. Mushfiq Mobarak and Dr Maarten Voors, and collaborators.

London, March 2024 Research, published in Nature, highlights a cost-effective approach to increasing COVID-19 vaccination uptake among rural populations in developing countries, using a simple and widely applicable intervention that improves access to vaccines.

The study, “Last-mile delivery increases vaccine uptake in Sierra Leone”, was conducted in Sierra Leone in 2022, one year into its COVID-19 vaccine roll-out. At the time, only 6-9% of the adults who took part in the intervention were immunised. The authors (Niccolò F. Meriggi, Mushfiq Mobarak, and Maarten Voors at the International Growth Centre, University of Oxford, Yale University School of Management and Wageningen University, and collaborators), examined whether improving access to the vaccine would increase this figure, having found high levels of vaccine acceptance in 10 low- and middle-income countries in a previous study in 2021.

With the Sierra Leone Ministry of Health and Sanitation, and international NGO, Concern Worldwide, the team conducted a randomised controlled trial with just over 20,000 Sierra Leoneans over age 12, living in 150 rural towns outside Sierra Leone’s national clinic network. Health workers took vaccines to communities where they set up temporary vaccination sites, provided information about the vaccine with community members, and administered it, augmenting the reach of existing clinic infrastructures.

100 villages were in the treatment group and 50 in the control group, with 5-9 people vaccinated on average in each village at baseline.

Within 48-72 hours of the intervention being introduced, vaccination rates increased by around 26 percentage points, and vaccination counts increased sevenfold, in the treatment group. In December 2022, Sierra Leone reached the WHO’s global target to immunise 70% of its adult population against COVID-19, and in March 2023, 7.8 million vaccine doses had been delivered.

This model, which is 76% cheaper than the average cost of similar interventions (about $80), has the potential to be replicated across developing countries with large rural populations, and similar transport, community, and infrastructure set-ups.* As transportation to reach villages accounted for a large share of this model’s costs, including multiple maternal and child health interventions on the same trip in future would also lower costs per person treated further.

This research comes at a crucial time. Developing countries are still recovering from the economic and health shocks of COVID-19, which included disruption to routine immunisation campaigns and increased risk of pandemic outbreaks in future, triggering disease recurrence and costly lockdowns.

The study adds to the range of approaches that are needed to increase vaccine uptake and can maximise resources. It provides a blueprint for policymakers, researchers, healthcare providers and NGOs to prioritise and optimise last-mile vaccine delivery, reducing the cost of vaccination campaigns and promoting sustainable and inclusive economic growth.

Meriggi, principal investigator said, “Our research shows that access was a binding constraint to the COVID-19 vaccination campaign in remote areas of Sierra Leone. Access, amongst other approaches like communication, is crucial to achieving vaccine equity in developing countries, and will likely be relevant to the new malaria vaccine roll-out and other health products and services.”

The research team has since been awarded funds from the US-based Social Science Research Council through its Mercury Project and from the International Growth Centre. The grants will be used to expand the model in this paper to a bundle of health products and services, including additional vaccines and maternal and child health interventions, and further explore its feasibility and cost-effectiveness. The first bundle, jointly decided between the Ministry of Health and the researchers, will include the COVID-19 vaccine, HPV vaccine for girls aged 10-12, and routine immunisations for children aged 0-6.

*As part of this study, the authors conducted a systematic literature review of 141 vaccination uptake RCT studies with 234 unique interventions. Only 33 (14%) reported the cost of the intervention per successfully administered vaccination. Most vaccination campaigns exceeded the US $33 benchmark in this study. Figure 6 in the study shows an analysis of “cost per vaccinated person” across 29 comparable interventions between 2000 – 2022. The cost of each intervention is calculated in “Cost per vaccine administered in 2000 USD” and does not include the cost of the vaccine itself. The cost per person in this study of US$ 33, is US$ 19.27 in 2000 USD. The mean value was US$ 83 (SD = 132) after dropping the most expensive approach of over US$ 2300 per shot.



Niccolò F. Meriggi

Niccolò is an applied microeconomist with a regional focus on sub-Saharan Africa. His research sits at the intersection of academia, policymaking and practice. He primarily uses experimental methods to understand policy and governance challenges, and test solutions to overcome these challenges under political, institutional, technical and resource constraints. Implementing those projects has involved wide-ranging collaboration with other scholars locally and internationally, significant international fundraising and developing skills in managing large and complex projects.

Niccolò has lived in all the countries where he has conducted research, including Sierra Leone, where he has been based for nearly eight years, working for the International Growth Centre (IGC). As part of his research, he regularly engages with policy-makers and practitioners to support reforms and achieve societal impact. He has successfully built close relationships with policymakers to design and implement creative and impactful research projects, and then operationalise key findings. Niccolò’s research has been published in the American Economic Review, the Journal of Development Economics, Nature, and Science Advances. He is presently a Postdoctoral Research Fellow at the Department of Economics and the Centre for the Study of the African Economies at the University of Oxford, a Postdoctoral Researcher at Wageningen University, and a Research and Policy Advisor at the International Growth Centre.

Mushfiq Mobarak

Ahmed Mushfiq Mobarak is the Jerome Kasoff ’54 Professor of Management and Economics at Yale University with concurrent appointments in the School of Management and in the Department of Economics. Mobarak is the founder and faculty director of the Yale Research Initiative on Innovation and Scale (Y-RISE).

Mobarak has several ongoing research projects in Bangladesh, Nepal, and Sierra Leone. He conducts field experiments exploring ways to induce people in developing countries to adopt technologies or behaviors that are likely to be welfare-improving. He also examines the complexities of scaling up development interventions that are proven effective in such trials. His research has been published in journals across disciplines, including Science, Nature, Econometrica,  American Economic Review, Review of Economic Studies, BMJ, the American Political Science Review, PNAS, Marketing Science, and Demography, and covered by the New York Times, The Economist, NPR, BBC, NBC, The Washington Post, Wall Street Journal, Science, Nature, and other media outlets around the world. He received a Carnegie Fellowship in 2017 and was named to the inaugural Vox list of 50 “scientists working to build a more perfect future” in 2022.

Mobarak collaborated with the government of Bangladesh and other institutions to devise evidence-based COVID response strategies in 2020. He collaborated with governments and NGOs in India, Pakistan, Nepal and Bangladesh to distribute facemasks to over 100 million people during the Delta and Omicron waves in 2021, based on the results of the NORM model. He began collaborating with the government of Sierra Leone on vaccine distribution in 2022, and set up an institutional partnership with WHO in 2023 to work on behavioural sciences for public health in Jamaica, Sierra Leone and other WHO member states.

Maarten Voors

Maarten is an Associate Professor at the Development Economics Group at Wageningen University. His main field is development economics. Maarten’s research focuses on incentives, institutions and behaviour in (post-conflict) developing countries. He uses a variety of methods including surveys, lab and field experiments and econometric analysis. Maarten’s geographic focus is sub-Saharan Africa. His recent projects include field experiments on formal and informal institutions, recruitment and monitoring (health) workers, rural electrification and technology adoption. Maarten is a member of the Wageningen Young Academy, EGAP and is a Fellow at the Cambridge Centre for Environment, Energy and Natural Resource Governance (C-EENRG). His research has been published in journals across disciplines, including Science Advances, Nature, American Economic Review, Quarterly Journal of Economics, Economic Journal, and elsewhere.

Contact information:

Annelise Andersen, Head of Communications, IGC
Email: [email protected]