Spatial Layout and Accessibility Evaluation of COVID-19 Vaccination Sites Based on Three Optimization Models: A Case Study of Tianhe District, Guangzhou

The outbreak of COVID-19 poses a serious threat to global public health, and vaccination is an effec-tive means of prevention. Studying the spatial lay-out and accessibility of COVID-19 vaccination sites is of great significance. The study analyzes the spatial distribution characteristics and accessibility of vacci-nation sites in the early stage of mass vaccination in Tianhe District, Guangzhou, based on GIS technology and combines three location allocation models: the p-median model, maximum covering location prob-lem (MCLP) model, and location set covering problem (LSCP) model to identify candidate COVID-19 vacci-nation sites for the proposed public service facilities. The study found that only 47 COVID-19 vaccination sites exist in the early stage, with a small overall num-ber, uneven spatial distribution, and trend of high ac-cessibility in the central but low accessibility in the north and south; after the proposed addition of 31 vac-cination sites, the overall distribution showed an even and dense distribution in the central and western re-gions, sporadic distribution in other regions, consis-tent with the distribution characteristics of residential communities. The areas where the accessibility of vac-cination sites increased by more than 500 m accounted for 41% of the total area, and the area served by vac-cination sites increased by 18%. Therefore, using the existing public service facilities to reasonably add the vaccination sites can improve the efficiency of vaccina-tion and safeguard the establishment of a herd immu-nity barrier.