Remarkable postvaccination spatiotemporal changes in United States rotavirus activity.

Analyses of US laboratory surveillance data during 1991 to 2004 established annual peak rotavirus activity occurred first in the Southwest and last in the Northeast. We compared spatiotemporal patterns during the 2 years preceding vaccine introduction in 2006 with the first 2 years following introduction. The postvaccine introduction years failed to demonstrate the typical Southwest to Northeast spread of rotavirus activity.