Josephine van Dongen

Chapter 6 142 Abstract Background: The WHO recommends research into non-specific effects of vaccination. For rotavirus vaccines, these have not yet been well established. We studied non-specific effects using data from a quasi-experimental before-after study comparing cohor ts of rotavirus vaccinated and unvaccinated infants with medical risk conditions up to 18 months of age. Methods : Infants were enrolled at six weeks of age before and after a stepped-wedge implementation of a risk-group based rotavirus vaccination program. Other infant vaccinations were administered according to the Dutch National Immunization Program and similar in both periods. Non-specific effect outcomes were prospectively collected using monthly questionnaires and included acute hospitalization (excluding for acute gastro-enteritis), monthly incidence of acute respiratory illness and eczema.We used time-to-event analysis and negative binomial regression to assess the effect of at least one dose of rotavirus vaccination for each of these outcomes. Findings :The analysis included 496 rotavirus unvaccinated and 719 vaccinated high-risk infants. In total, 1067 (88%) were premature, 373 (31%) small for gestational age and 201 (17%) had a congenital pathology.The adjusted hazard ratio for first acute hospitalization was 0.91 (95%CI 0.76;1.16) for rotavirus vaccinated versus unvaccinated infants. Adjusted incidence rate ratio for acute respiratory illness was 1.05 (95%CI 0.96;1.15) and for eczema 0.89 (95%CI 0.69;1.15). Interpretation :The results suggest no, or minimal non-specific effects from rotavirus vaccination on non-target diseases in high-risk infants.