Hospitalisations due to respiratory syncytial virus infection in children with Down syndrome before and after palivizumab recommendation in Japan

AIM: Down syndrome has been considered an independent risk factor for respiratory syncytial virus (RSV) infection. Palivizumab, an anti-RSV humanised monoclonal antibody, was currently approved for all children with Down syndrome in Japan. To investigate the change in RSV-associated hospitalisation (RSVH) rates before and after the universal approval of palivizumab in Japan in 2013, we conducted a nationwide retrospective survey. METHODS: We conducted a nationwide, retrospective, questionnaire survey across paediatric institutions in Japan. The recruited children with Down syndrome were divided into two groups: those born April 2010 to March 2013 (2010-2012 cohort) and those born April 2013 to March 2016 (2013-2015 cohort). RESULTS: Of the 664 institutions, 321 (48.3%) replied, and a total of 3929 children with Down syndrome were registered. The percentage of children who received palivizumab increased from 49.2% to 82.2%. The cumulative RSVH rate showed a decreased trend in the 2013-2015 cohort (OR, 0.83; 95%CI, 0.63-1.10), while the rate of these children (without CHD and born at a gestational age ≥ 36 weeks) was significantly decreased in the 2013-2015 cohort (OR, 0.56; 95%CI, 0.34-0.92). CONCLUSION: The cumulative RSVH rate tended to be decreased after approval for all children with Down syndrome although the result was not significant.