Viral Acute Respiratory Illnesses in Young Infants Increase the Risk of Respiratory Readmission

Background: Respiratory viruses cause acute respiratory illness (ARI) in early childhood, but their effect on subsequent ARI admissions is not fully understood. This study aimed to determine the association between initial ARI admission because of viruses including human rhinovirus (HRV), respiratory syncytial virus (RSV), human adenovirus (HAdV) and human metapneumovirus (hMPV) and the risk of ARI readmission in children. Methods: Clinical information and nasopharyngeal swab samples were collected from children <2 years old at their initial ARI admission in Nha Trang, Vietnam, from January 2007 to April 2012. The incidence of ARI readmission during the follow-up period (initial admission to 5 years of age) was compared between children with and without 1 of 13 respiratory viruses (influenza virus A, influenza virus B, RSV, hMPV, parainfluenza virus-1, parainfluenza virus-2, parainfluenza virus-3 and parainfluenza virus-4, HRV, human coronavirus-229E, human coronavirus-OC43, HAdV and human bocavirus) at initial admission. Results: A total of 1941 children were enrolled in the study. Viruses were detected in 1254 (64.6%) children at enrollment; HRV, RSV, HAdV and hMPV were detected in 499 (25.7%), 439 (22.6%), 156 (8.0%) and 47 (2.4%) children, respectively. During the follow-up period (4572.7 person-years), 277 children were readmitted with ARI. Virus-related ARI initial admission was associated with an increased risk of ARI readmission for children who were initially admitted before 6 months of age (adjusted rate ratio, 1.6; 95% confidence interval: 1.1-2.5). HAdV (4.6; 1.8-11.9), hMPV (20.4; 6.2-66.9) and HRV (1.6; 1.0-2.4) were independently associated with the outcome. These associations were not observed for children whose initial admission occurred after 6 months of age. Conclusions: HAdV-, hMPV- and HRV-related initial ARI admissions, when occurring during early infancy, increased the risk of subsequent ARI-related readmission.