Prevalence characteristics of influenza viruses in children in Beijing during 2014-2015 and 2015-2016 influenza seasons

Abstract

To compare the prevalence characteristics of influenza viruses in children in Beijing during 2014-2015 and 2015-2016 influenza seasons. Throat swabs were collected weekly from children with influenza-like illnesses who visited in Children's Hospital affiliated to Capital Institute of Pediatrics during the period from September 2014 to May 2016.Influenza viruses A and B viruses were detected by real-time RT-PCR, followed by identification of H3N2, H1N1pdm, B/Victoria-like and B/Yamagata-like.The prevalence characteristics of influenza viruses was estimated by means of descriptive statistics.The t test and chi-square test were used to compare median age and gender ratio of infected children among different types of influenza viruses. Out of 1 821 throat swabs collected, 139 (7.6%) were positive for H3N2 and 43 (2.4%) for H1N1pdm and 204 (11.2%) for influenza B virus, including 108 for B/Victoria-like and 96 for B/Yamagata-like.The median age of H1N1pdm infected children ((3.3±2.2) years) was significantly younger than that of H3N2 ((4.7±3.2) years) and influenza B virus((4.9±2.8) years) (H1N1pdm vs. H3N2: t=2.848, P=0.002; H1N1pdm vs. influenza B, t=3.682, P=0.000). Two epidemic peaks were presented in 2014-2015 influenza season, dominated definitely by H3N2 and B/Yamagata-like, respectively, while one delayed peak started at the 51(st) week, 2015, co-circulated with H3N2, H1N1pdm and influenza B viruses, among which B/Victoria-like virus was predominant during the 2015-2016 season. Prevalence characteristics of influenza viruses are different between 2014-2015 and 2015-2016 influenza seasonal epidemics in children in Beijing. It is important to monitor the genetic variations of influenza viruses and to keep close attention to influenza B virus as well as influenza A virus.