Seasonal Variations of Respiratory Syncytial Virus Infection among the Children under 60 Months of Age with Lower Respiratory Tract Infections in the Capital Area, the Republic of Korea, 2008-2011

Respiratory Syncytial Virus Seasonality: A Global Overview

Respiratory syncytial virus (RSV) is the leading cause of acute lower respiratory infections in children. By the age of 1 year, 60%-70% of children have been infected by RSV. In addition, early-life RSV infection is associated with the development of recurrent wheezing and asthma in infancy and childhood. The need for precise epidemiologic data regarding RSV as a worldwide pathogen has been growing steadily as novel RSV therapeutics are reaching the final stages of development. To optimize the prevention, diagnosis, and treatment of RSV infection in a timely manner, knowledge about the differences in the timing of the RSV epidemics worldwide is needed. Previous analyses, based on literature reviews of individual reports obtained from medical databases, have failed to provide global country seasonality patterns. Until recently, only certain countries have been recording RSV incidence through their own surveillance systems. This analysis was based on national RSV surveillance reports and medical databases from 27 countries worldwide. This is the first study to use original-source, high-quality surveillance data to establish a global, robust, and homogeneous report on global country-specific RSV seasonality.

Effect of Prophylactic Palivizumab on Admission Due to Respiratory Syncytial Virus Infection in Former Very Low Birth Weight Infants with Bronchopulmonary Dysplasia

The aim of this study was to observe the effects of prophylactic palivizumab on hospitalization secondary to respiratory syncytial virus (RSV) infection (RSVhospitalization) in former very low birth weight infants (VLBWI) with bronchopulmonary dysplasia (BPD). This study also sought to identify the risk factors of RSVhospitalizationin this particular infant population. A prospective observational study was conducted between September 2007 and April 2008 in seven Korean hospitals. Children with a history of very low birth weight, a diagnosis of BPD and who were <2 yr old at the onset of the RSV season were included in this study. Palivizumab injections were administered monthly for a maximum of five months during the RSV season. RSVhospitalization rates were reviewed, and RSVhospitalization rates between subgroups were categorized by gestational age, birth weight, and duration of ventilator care. A total of 90 subjects completed the follow-up interviews. The mean gestational age at birth was 26.1±1.7 weeks, and the mean birth weight was 889.4±222.2 g. The incidence of RSVhospitalization in the study population was 8.9% (8/90), and the mean hospital stay was 11.0±5.5 days, including one death. There were no statistically significant differences in the patients' demographic characteristics or risk factors for RSV hospitalization. When subgroup analyses were conducted, there were still no statistically significant differences. The administration of palivizumab prophylaxis during the entire RSV season is important in VLBWI with BPD, regardless of their gestational age and birth weight, or previous ventilator dependency.

Epidemiologic differences of four major respiratory viruses between children, adolescents, and adults in Korea

The purpose of this study was to investigate the epidemiology of four major respiratory viruses among the Korean population. This retrospective study was conducted over four years, from January 2005 to December 2008. Among a total of 23,806 specimens, 5512 virus isolates underwent culture for influenza A and B viruses (IFA/B), parainfluenza virus (PIV), respiratory syncytial virus (RSV), and adenovirus (ADV). Patients were divided into two groups: children/adolescents and adults. The viruses detected in specimens from children/adolescents included PIV (7.8%), RSV (7.3%), ADV (4.0%), IFA (2.9%), and IFB (2.2%). In adults, IFB (5.6%), IFA (4.4%), RSV (1.1%), PIV (0.5%), and ADV (0.2%) were detected, thus demonstrating two distinct patterns of virus infection. Influenza viruses had similar seasonal patterns and periods of infection among children/adolescents and adults; however, the isolation rate in adults was slightly higher than that in children and adolescents. Correlation coefficient analysis based on weekly seasonal patterns indicated that influenza viruses were detected a week earlier in children than in adults. RSV, PIV, and ADV did not show similar trends between the two age groups due to low detection rates and sporadic isolations among adult patients. Of note, different respiratory viruses should be considered depending on patient age when a clinical respiratory viral infection is suspected. Furthermore, in the case of influenza, a preceding epidemic among a pediatric population could be useful to predict a subsequent epidemic among adults.