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Background: Estimates of rotavirus vaccine effectiveness (VE) in the United States appear higher in years with more rotavirus activity. We hypothesized rotavirus VE is constant over time but appears to vary as a function of temporal variation in local rotavirus cases and/or misclassified diagnoses.Methods: We analyzed 6 years of data from eight US surveillance sites on 8- to 59-month olds with acute gastroenteritis symptoms. Children's stool samples were tested via enzyme immunoassay (EIA); rotavirus-positive results were confirmed with molecular testing at the US Centers for Disease Control and Prevention. We defined rotavirus gastroenteritis cases by either positive on-site EIA results alone or positive EIA with Centers for Disease Control and Prevention confirmation. For each case definition, we estimated VE against any rotavirus gastroenteritis, moderate-to-severe disease, and hospitalization using two mixed-effect regression models: the first including year plus a year-vaccination interaction, and the second including the annual percent of rotavirus-positive tests plus a percent positive-vaccination interaction. We used multiple overimputation to bias-adjust for misclassification of cases defined by positive EIA alone.Results: Estimates of annual rotavirus VE against all outcomes fluctuated temporally, particularly when we defined cases by on-site EIA alone and used a year-vaccination interaction. Use of confirmatory testing to define cases reduced, but did not eliminate, fluctuations. Temporal fluctuations in VE estimates further attenuated when we used a percent positive-vaccination interaction. Fluctuations persisted until bias-adjustment for diagnostic misclassification.Conclusions: Both controlling for time-varying rotavirus activity and bias-adjusting for diagnostic misclassification are critical for estimating the most valid annual rotavirus VE. [ABSTRACT FROM AUTHOR]

Immunization information systems (IISs) are confidential, population-based systems that contain immunization data for children, and, in some cases, adults, within a geographic area. There are generally two models for participation in an IIS, termed voluntary exclusion or "opt-out" and voluntary inclusion or "opt-in." Using the Texas opt-in consent system and statewide IIS (ImmTrac), we describe the costs associated with obtaining opt-in consent in hospitals as part of the birth registration process and in provider offices for children without prior consent. We also estimate the costs associated with a hypothetical opt-out system. Between October 2006 and August 2007, project staff conducted on-site time studies for patients in 8 birthing hospitals (n = 281), 16 provider offices (n = 131), and ImmTrac state offices in Austin, Texas (n = 100). Total costs per child and costs per year were estimated using a time-and-motion study in which the time associated with discussing ImmTrac and obtaining ImmTrac consent was measured. The annual costs associated with obtaining consent for Texas' opt-in IIS are estimated at $1 389 804.61. The average per child cost associated with ImmTrac consent completed at birth is $2.00, whereas the per child cost for consent completed in provider offices is $2.64. The annual costs of operating an alternative, opt-out system are estimated at $110 714.03, or $0.29 per child. This cost analysis demonstrated that the proposed opt-out costs were substantially less than the actual opt-in model currently utilized. Changing to an opt-out system could redirect limited healthcare funding to more critical areas such as vaccine purchasing and administration.