Longer-term Direct and Indirect Effects of Infant Rotavirus Vaccination Across All Ages in the United States in 2000-2013: Analysis of a Large Hospital Discharge Data Set

Abstract

Background: Rotavirus disease rates dramatically declined among children <5 years of age since the rotavirus vaccine was introduced in 2006; population-level impacts remain to be fully elucidated.

Methods: Data from the Healthcare Cost and Utilization Project State Inpatient Databases were used to conduct a time-series analysis of monthly hospital discharges across age groups for acute gastroenteritis and rotavirus from 2000 to 2013. Rate ratios were calculated comparing prevaccine and postvaccine eras.

Results: Following vaccine introduction, a decrease in rotavirus hospitalizations occurred with a shift toward biennial patterns across all ages. The 0-4-year age group experienced the largest decrease in rotavirus hospitalizations (rate ratio, 0.14; 95% confidence interval, .09-.23). The 5-19-year and 20-59-year age groups experienced significant declines in rotavirus hospitalization rates overall; the even postvaccine calendar years were characterized by progressively lower rates, and the odd postvaccine years were associated with reductions in rates that diminished over time. Those aged ≥60 years experienced the smallest change in rotavirus hospitalization rates overall, with significant reductions in even postvaccine years compared with prevaccine years (rate ratio, 0.51; 95% confidence interval, .39-.66).

Conclusions: Indirect impacts of infant rotavirus vaccination are apparent in the emergence of biennial patterns in rotavirus hospitalizations that extend to all age groups ineligible for vaccination. These observations are consistent with the notion that young children are of primary importance in disease transmission and that the initial postvaccine period of dramatic population-wide impacts will be followed by more complex incidence patterns across the age range in the long term.

Keywords: gastrointestinal illness; hospitalizations; rotavirus; vaccination.

Figure 1.

Monthly all-cause acute gastroenteritis (A–D) and rotavirus gastroenteritis (E–H) hospitalizations per 10000 age-specific population, 2000–2013. Data are from 26 US states from the Healthcare Cost and Utilization Project’s State Inpatient Databases; see Data Sources, in Methods, for the full list of states. Data are full-year data (not restricted to January–June), for the purpose of visualizing the patterns in hospitalization rates. Dotted lines in parts (A–D) represent up-to-date vaccine coverage among children aged 19–35 months (2 or 3 doses, depending on vaccine manufacturer); the vertical black dashed lines denote introduction of rotavirus vaccine.

Figure 2.

Monthly all-cause acute gastroenteritis (AGE) (A–D) and rotavirus gastroenteritis (RVGE) (E–H) hospitalization rate ratios (RRs) comparing prevaccine (2000–2006) and postvaccine (2008–2013) periods by year. Data are from 26 US states from the Healthcare Cost and Utilization Project’s State Inpatient Databases; see Data Sources, in Methods, for the full list of states. A–D, AGE data based on negative binomial regression using a sequential (continuous) time variable to control for potential exogenous secular trends, restricted to the rotavirus season (January–June). E–H, RVGE data based on negative binomial regression controlling for the pre-2004 period, using an indicator variable to account for the increase in RVGE hospitalization rates that occurred just before 2004, including all months.