Long-term impact of self-financed rotavirus vaccines on rotavirus-associated hospitalizations and costs in the Valencia Region, Spain

Alejandro Orrico-Sanchez, Mónica López-Lacort, Silvia Pérez-Vilar, Javier Díez-Domingo

Rotavirus vaccines are available in Spain from 2007. They are recommended by the Spanish Pediatric Association, but not funded by the National Health System (NHS) and its coverage rate reached 40-50%. The hospitalization rate reduction of rotavirus caused gastroenteritis (RVAGE) directly attributable to vaccination remains unclear due to the large differences described in published studies, ranging from 14 to 44.5% in children <5 years of age, even with similar vaccination coverage. These results could be partly explained by variability in hospitalization policies, different study designs and the timeframe of observation. In addition, the direct economic impact of the reduction of hospitalizations has never been estimated. Therefore, there is a need to analyze the long-term impact of rotavirus vaccines on RVAGE and all cause gastroenteritis (AGE) hospitalizations and the national health system associated costs, minimizing potential confounders or biases. A population-based, ecological study using the hospital discharge registry's Minimum Basic Data Set (MBDS) and the vaccine register (SIV) was performed, among Valencia Region's children <5 years old, during 2002 - 2015. RVAGE and AGE hospitalization risk was analyzed by vaccine coverage and adjusted by the total hospitalization rate for all causes to avoid external biases. The impact of AGE-associated health care utilization in prevaccine (2003-2006) versus postvaccine (2008-2014) years was also assessed. After vaccines licensure, the incidence of RVAGE-associated hospitalizations decreased markedly. A general vaccine coverage-related reduction in RVAGE or AGE-hospitalizations risk was observed in all age groups. Compared with unvaccinated children, RVAGE hospitalization risk decreased by 67% (95% CI: 55-67), 71% (95% CI: 58-81) and 68% (95% CI: 18-92) in children 0, 1 and 4 years of age, respectively, with a vaccination coverage between 40 and 42%. Overall, the hospital related costs were reduced around EUR 6 Mill per 10(5) children in 7 years. Despite the low-medium vaccine coverage, the introduction of rotavirus vaccines had a specific coverage-related response impact in the hospitalizations for RVAGE and AGE in children <5 years and their use substantially reduced hospital related costs. The model used reassures that the estimated impact is due to the vaccination and not to other external factors.