Objective: We sought to determine the impact of rotavirus vaccine implementation on gastroenteritis (GE)-related calls to a large telephone triage service in Tennessee.
Methods: Total and GE-related calls received by the Vanderbilt Telephone Triage Program for children <5 years of age were examined from May 1, 2004 to April 30, 2010. Time series adapted Poisson regression models were used to compare weekly GE-related call proportions between the prevaccine (May 2004 to April 2007) and postlicensure (May 2007 to April 2010) periods. Separate models compared GE-related call proportions in the historical rotavirus (February to April) and nonrotavirus (May to January) seasons. Associations between call data and laboratory-confirmed rotavirus detections and regionally reported norovirus activity were also assessed.
Results: There were 156362 total calls and 19731 GE-related calls. Annual GE-related call proportions declined by 8% (95% confidence interval, 3%-12%) in the postlicensure period; declines ranging from 23% to 31% occurred during the historical rotavirus season in all 3 postlicensure years. No declines occurred in the nonrotavirus season. After vaccine licensure, reductions in laboratory-confirmed rotavirus activity were associated with declines in GE-related call proportions. Peak GE-related call proportions in the postlicensure period occurred earlier than in prevaccine years and were not strongly associated with laboratory-confirmed rotavirus but instead showed good correlation with norovirus outbreaks.
Conclusions: A decline in GE-related call proportions among young children after rotavirus vaccine licensure was documented by using a novel surveillance platform that captures mild GE not detected in other surveillance systems. Since rotavirus vaccine licensure, peak call proportions correlate with regional norovirus activity, highlighting the role of that pathogen in community GE.