Spatio-temporal impact of self-financed rotavirus vaccination on rotavirus and acute gastroenteritis hospitalisations in the Valencia region, Spain

Background: Several studies have shown a substantial impact of Rotavirus (RV) vaccination on the burden of RV and all-cause acute gastroenteritis (AGE). However, the results of most impact studies could be confused by a dynamic and complex space-time process. Therefore, there is a need to analyse the impact of RV vaccination on RV and AGE hospitalisations in a space-time framework to detect geographical-time patterns while avoiding the potential confusion caused by population inequalities in the impact estimations. Methods: A retrospective population-based study using real-world data from the Valencia Region was performed among children aged less than 3years old in the period 2005-2016. A Bayesian spatio-temporal model was constructed to analyse RV and AGE hospitalisations and to estimate the vaccination impact measured in averted hospitalisations. Results: We found important spatio-temporal patterns in RV and AGE hospitalisations, RV vaccination coverage and in their associated adverted hospitalisations. Overall, similar to 1866 hospital admissions for RV were averted by RV vaccination during 2007-2016. Despite the low-medium vaccine coverage (similar to 50%) in 2015-2016, relevant 36 and 20% reductions were estimated in RV and AGE hospitalisations respectively. Conclusions The introduction of the RV vaccines has substantially reduced the number of RV hospitalisations, averting similar to 1866 admissions during 2007-2016 which were space and time dependent. This study improves the methodologies commonly used to estimate the RV vaccine impact and their interpretation.