Data-driven exploration of ‘spatial pattern-time process-driving forces’ associations of SARS epidemic in Beijing, China

Wang, Jin-Feng; Christakos, George; Han, Wei-Guo; Meng, Bin

The present work proposed a methodological framework to determine the main features of SARS transmission during the Beijing epidemic of 2003 using various datasets and space-time statistics techniques. Epidemic determinants and the relevant statistics are pair-wise linked in a space-time context, which means that the study of determinant associations can considerably enhance the mainstream epidemic analysis and improve the understanding of previously undetected relationships within the epidemic system. Several interesting findings were obtained. Spatial neighbourhood is a major component of epidemic spread modelling, whereas coupling spatial transmission with population density and healthcare workers was sporadically significant. Changes in the spatial spread of SARS over time indicated which intervention measures are likely to be most effective at different phases of the outbreak. When the epidemic is growing via diffused infection, efficient intervention measures include isolating cases and reducing inter-regional movement. When cases of the disease appear in clusters, resources should be directed towards curbing transmission within localities that have a high incidence of infection. Our results suggested that improving control measures at the local level would have been the most efficient approach, before the end of April, 2003. Local intervention strategies include quarantine of family members. Once these measures take effect, transmission is reduced substantially and becomes dominated by more remote contacts. The evidence that diffusion of infections drove the declining stage of the outbreak may indicate that the measures were successfully controlling local transmission.