A global bibliometric analysis of research productivity on vaccine hesitancy from 1974 to 2019.

Vaccine hesitancy is a phenomenon where individuals delay or refuse to take some or all vaccines. The objective of this study was to conduct a global bibliometric analysis of research productivity and identify country level indicators that could be associated with publications on vaccine hesitancy. We searched PubMed and Web of Science for publications from 1974 to 2019, and selected articles focused on behavioral and social aspects of vaccination. Data on country-level indicators were obtained from the World Bank. We used Spearman's correlation and zero-inflated negative-binomial regression models to ascertain the association between country level indicators and the number of publications. We identified 4314 articles, with 1099 eligible for inclusion. The United States of America (461 publications, 41.9%), Canada (84 publications, 7.6%) and the United Kingdom (68 publications, 6.2%) had the highest number of publications. Although various country indicators had significant correlations with vaccine hesitancy publications, only gross domestic product (GDP) and gross national income (GNI) per capita were independent positive predictors of the number of publications. When the number of publications were standardized by GDP, the Gambia, Somalia and Malawi ranked highest in decreasing order. The United States, Canada and United Kingdom ranked highest (in that order) when standardized by current health expenditure. Overall, high-income countries were more productive in vaccine hesitancy research than low-and-middle-income countries. There is a need for more investment in research on vaccine hesitancy in low-and-middle-income countries.