A space–time cluster of adverse events associated with canine rabies vaccine

Electronic medical records of a large veterinary practice were used for surveillance of potential space–time clustering of adverse events associated with rabies vaccination in dogs. The study population was 257,564 dogs vaccinated in 169 hospitals in 13 US metropolitan areas during a 24-month period. Using a scan statistic for population rate data, significant space–time clusters were identified involving the Atlanta and Tampa/St. Petersburg areas during a 4-month period. Separate spatial–temporal analyses of these cities using coordinates for individual address coordinates identified one significant patient cluster (P = 0.002), associated with a 23.26 km-radius area in Atlanta (20 adverse events in 702 dogs; 2.85%) from November 2002 through February 2003. This percentage of adverse events was significantly increased after adjustment for host-related factors and the number of concurrent vaccinations.