The Epidemiology of Respiratory Syncytial Virus Lower Respiratory Tract Infection on Young Children

Abstract

Reply: We thank Cooper and colleagues for their comments on our article and that by Simões and co-workers.1,2 They bring up the highly interesting question what incidence should be considered substantial. Simões found that the incidence of respiratory syncytial virus (RSV) lower respiratory tract infection (LRI) in patients with age 0–2 months, 3–5 months and 6–8 months is 0, 50 and 198, respectively, per 1000 child-years.1 These numbers are in-line with the accumulated cohort data from the Utrecht RSV Research group.2 These studies allow for the conclusion that RSV bronchiolitis is relatively rare during the first months of life, but when it occurs, the course of disease is severe. It seems obvious that both incidence and severity of RSV LRI during infancy determine the burden of disease. Thus, we agree with Cooper and colleagues that the burden of RSV LRI in children 3–6 months is quite substantial despite the consistent observation that incidence is lower than in children 7–12 months. Louis Bont, MD, PhD Michiel L. Houben, MD Department of Pediatrics,Utrecht RSV Research Group, University Medical Center Utrecht, Utrecht, The Netherlands