Medium- to Long-Term Impact of Rotavirus Vaccination on Hospital Care in Belgium: A 7-Year Follow-Up of the Rotavirus Belgium Impact Study (RotaBIS)

Abstract

Introduction: Rotavirus (RV) vaccination was introduced in Belgium in 2006. With the high uptake it had (>85%), a sharp decline in hospitalizations was observed during the first years after vaccine introduction. The objective of this study was to investigate whether this decline was maintained and to simulate projections.

Methods: The Rotavirus Belgium Impact Study allowed an analysis of the RV vaccine impact amongst children in 11 hospitals in Belgium over a 9-year period (2005-2013) with 2 years pre- and 7 years post-vaccine introduction. Results were compared by year and by subsequent birth cohort aging up to 5 years. The two different analysis methods helped dismantling the different (direct and indirect) effects of vaccine protection to simulate future hospitalization trends.

Results: During the whole observation period, 40,552 RV detection tests were performed of which 5832 were positive (14.4%). After RV vaccine introduction, a significant reduction in number of tests performed (-38%) was combined with a dramatic drop in numbers of positive tests (-76.6%). The decreases were spectacular during the first two years of vaccine introduction; after that period, the decrease flattened. Cross-sectional comparison with cohort data showed that the initial drop was heavily influenced by the herd effect of the vaccine. Cohort analysis demonstrated a low rate of residual disease over time, suggesting another infection source other than the child population.

Conclusion: The residual disease will be maintained in the community when a same vaccination strategy is continued over time, starting vaccination of children only at 6 weeks' time.

Funding: GlaxoSmithKline Biologicals SA.

Trial registration: ClinicalTrials.gov identifier, NCT01563146.

Keywords: Children; Gastroenteritis; Hospitalization; Rotavirus; Vaccination.

Fig. 1

Number of RV-negative and RV-positive tests performed per year in the 11 participating centers Nbr number, RV rotavirus

Fig. 2

Distribution of RV-positive tests by age-group and year. Nbr number, RV rotavirus, mo months, yrs years

Fig. 3

Comparing observed data (a) with simulations of adding residual disease over time (b); with fixed reduction in RV-positive tests without residual disease (c); vaccine waning (−10% per year) (d); changing vaccine coverage rate (85% to 65%) (e). Nbr number, RV rotavirus

Fig. 4

Difference in proportion of RV-positive tests during the post-vaccination period (2012 and 2013) compared with the pre-vaccination period (2006) in each hospital center (code). RV rotavirus