Measuring and validating spatial accessibility to Covid-19 vaccination sites: a case study in England

The global Covid-19 pandemic has caused numerous deaths and illnesses and posed unprecedented social and economic challenges to many countries. One of the key strategies to contain the pandemic is mass vaccination. While it is essential to ensure safe and easy accessibility to Covid-19 vaccines for all communities, limited research has been carried out to understand and validate the spatial accessibility of these vaccines. This study addresses this gap by measuring and validating the spatial accessibility to Covid-19 vaccines with a particular focus on England, United Kingdom. More specifically, we compare three floating catchment area (FCA) methods with differing parameters for measuring the small-scale spatial accessibility to vaccination services. Then, we calibrate these accessibility measurements using a beta regression model and the reported vaccination uptake rates. The results show that the three-step FCA method with a distance parameter of 30 miles is the optimal model for measuring the spatial accessibility to Covid-19 vaccines. The findings provide an improved understanding of the spatial inequality of vaccine services. Further, the framework of calibrating spatial accessibility to vaccine services is generalisable to other types of healthcare services.