Diarrhea-associated hospitalizations among US children over 2 rotavirus seasons after vaccine introduction.

OBJECTIVE: After implementation of rotavirus vaccination in 2006, large decreases in rates of severe diarrhea among US children occurred in 2007-2008. We ascertained whether these decreases were sustained in 2008-2009.

METHODS: We examined hospital discharge data from a national network of pediatric hospitals and compared all-cause diarrhea-related and rotavirus-specific hospitalizations in 3 prevaccine rotavirus seasons (2003-2006) with those in 2 postvaccine seasons (2007-2008 and 2008-2009) among children <5 years of age. We defined rotavirus seasons using data from a national laboratory surveillance network.

RESULTS: At 62 consistently reporting hospitals, a median of 15 645 diarrhea-related hospitalizations (range: 14 881-16 884 hospitalizations) occurred each rotavirus season among children <5 years of age in 2003-2006. Compared with this median, all-cause diarrhea-related hospitalizations decreased by 50% (n = 7760) in 2007-2008 and by 29% (n = 11 039) in 2008-2009. In 2007-2008, reductions of 47% to 55% were seen for all age groups, including vaccine-ineligible children ≥2 years of age (48%). In 2008-2009, these reductions decreased in magnitude, especially among children ≥2 years of age (17%). Decreases in 2007-2008 and 2008-2009 were similar in the Northeast and West, but decreases were smaller in 2008-2009, compared with 2007-2008, in the Midwest and South.

CONCLUSIONS: Compared with prevaccine seasons, decreases in diarrhea- and rotavirus-associated hospitalizations seen in 2007-2008 were sustained in 2008-2009 but were somewhat smaller. Given the variability in diarrhea-related hospitalization trends over the 2 postvaccine seasons according to age group and region, continued surveillance is required for full assessment of the impact of rotavirus vaccination.