Population Health

Boosting vaccination coverage

Data visualization of the worldVaccination coverage rates are affected by multiple and varied societal and personal factors​. To better understand these factors at a global scale, the University of Washington Population Health Initiative led an interdisciplinary research team that undertook a study that ended in February 2023 to better understand how countries can realistically improve vaccination coverage, and how such improvement will affect the overall burden of vaccine-preventable diseases in that country.

Specifically, the project sought to:

  • Identify countries of high, medium and low socio-demographic index that have been most successful at improving immunization rates over the past 10 years.
  • Identify the most important factors that have contributed to the improvements in the immunization rate for the best-performing country in the low socio-demographic index group.
  • Develop a Vaccination Improvement Potential Index (VIP) based on the relative importance of the factors leading to improved immunization rates.

Major findings from the study included:

  • Nigeria, Liberia and the Central African Republic were positive outliers in vaccination improvement​ over the last decade due to efforts to mitigate the effects of major public health emergencies
  • Vaccination Improvement Potential, in general, has increased across most regions of the world in last three decades​, although major gaps remain
  • Regional threats to Vaccine Improvement Potential include ​growing levels of vaccine mistrust in Western Europe and East and Southeast Asia, low levels of health expenditure and health system investment in Sub-Saharan Africa​ and low levels of socio-demographic development in South Asia​

Findings from this project can support policymakers in better understanding what a country’s vaccination coverage should be, and also where it stands relative to other countries at a similar stage of socio-demographic development. Furthermore, this research also offers insights into how a country can realistically improve its vaccination coverage, and how that improvement will affect the overall burden of vaccine-preventable diseases.

The UW project team included faculty, students and staff from the College of Engineering, the Information School, School of Medicine, School of Public Health and Population Health Initiative.

Read the Final Report View the VIP Index

Funding Acknowledgement

This study was funded by a research grant from the Investigator-Initiated Studies Program of Merck Sharp & Dohme Corp (MISP Reference Number 60343). The findings and opinions expressed in the report are those of the authors and do not necessarily represent those of Merck Sharp & Dohme Corp.