Creation of a Global Vaccine Risk Index

Abstract

The World Health Organization has identified vaccine hesitancy as one of its top ten global health threats for 2019. Efforts are underway to define the factors responsible for reductions in vaccine confidence. However, as global measles cases accelerated beginning in 2018, it became evident that additional factors were promoting measles re-emergence, including war, political and socio-economic collapse, shifting poverty, and vulnerability to weather events and climate change. Accordingly, we propose a Global Vaccine Risk Index (VRI) to consider these variables as a more comprehensive means to identify vulnerable nations where we might expect measles and other vaccine-preventable diseases to emerge or re-emerge. In Sub-Saharan African and Middle Eastern nations, conflict and political instability predominated as the basis for high vaccine risk scores, whereas in Southeast Asian countries, the major reasons included climate variability, current levels of measles vaccination coverage, and economic and educational disparities. In Europe, low vaccine confidence and refugee movements predominated, while in the Americas, economic disparities and vaccine confidence were important. The VRI may serve as a useful indicator and predictor for international agencies committed to childhood immunizations and might find relevance for accelerating future COVID19 vaccination programs.

Fig 1. Spearman correlations between the variables involved in derivation of VRI.

The colored vertical bar shows Spearman’s correlation between the variables with the intensity of color indicating the increasing absolute correlation. Red and blue areas in the bar correspond to <0 to-1 and> 0 to 1 Spearman correlation values, respectively.

Fig 2. Steps in creating the VRI.

The boxes show the initial number of variables and intermediate steps to filter the variables and countries for the final vaccine risk index factor analysis calculation.

Fig 3. Heat map of Vaccination Risk Indices.

Darker colors indicate a higher VRI score, indicating greater outbreak risk. *Generated using public domain map data from https://www.naturalearthdata.com/.

Fig 4. Factor score distributions by WHO Regions.