Trends in national rotavirus activity before and after introduction of rotavirus vaccine into the national immunization program in the United States, 2000 to 2012.

BACKGROUND: Rotavirus vaccine introduction in the United States in 2006 led to substantial declines in rotavirus detections during 2007 to 2010. To further evaluate the long-term impact of the vaccine program, we assessed trends in rotavirus testing and detection in the 2010 to 2011 and 2011 to 2012 seasons compared with prevaccine seasons from 2000 to 2006.
METHODS: We examined data from July 2000 to June 2012 from 50 to 70 laboratories reporting to the National Respiratory and Enteric Viruses Surveillance System to compare rotavirus season timing and peak activity in the pre- and postvaccine introduction eras. To assess trends in rotavirus testing and detection, we restricted the analyses to 25 laboratories that consistently reported for ≥ 26 weeks for each season from 2000 to 2012.
RESULTS: The threshold for the start of the rotavirus season was never achieved nationally during the 2011 to 2012 season, and the 2010 to 2011 season was 8 weeks shorter in duration than the prevaccine baseline. During these seasons, nationally, the number of positive rotavirus tests declined 74%-90% compared with the prevaccine baseline and the total number of tests performed annually declined 28%-36%. The annual proportion positive at the 25 consistently reporting laboratories remained below 10% in both seasons compared with a prevaccine baseline median of 26%. A pattern of biennial increases in rotavirus activity emerged during the 5 postvaccine seasons from 2007 to 2012, but activity remained substantially below prevaccine levels.
CONCLUSIONS: A substantial and sustained decline in rotavirus activity below the prevaccine baseline was observed in all 5 postvaccine introduction years, affirming the long-term health benefits of the US rotavirus vaccination program.