title: Respiratory Syncytial Virus and Other Viral Infections among Children under Two Years Old in Southern Vietnam 2009-2010: Clinical Characteristics and Disease Severity.
abstract: BACKGROUND
  Despite a high burden of respiratory syncytial virus (RSV) infections among children, data on demographic and clinical characteristics of RSV are scarce in low and middle income countries. This study aims to describe the viral etiologies, the demographic, epidemiological, and clinical characteristics of children under two years of age who were hospitalized with a lower respiratory tract infections (LRTI), focusing on RSV (prevalence, seasonality, subgroups, viral load) and its association with disease severity.
  
  
  METHODS
  A prospective study among children under two years of age, hospitalized with LRTI was conducted in two referral pediatric hospitals in Ho Chi Minh City, Vietnam, from May 2009 to December 2010. Socio-demographic, clinical data and nasopharyngeal swabs were collected on enrolment and discharge. Multiplex real-time RT-PCR (13 viruses) and quantitative RSV RT-PCR were used to identify viral pathogens, RSV load and subgroups.
  
  
  RESULTS
  Among 632 cases, 48% were RSV positive. RSV infections occurred at younger age than three other leading viral infections i.e rhinovirus (RV), metapneumovirus (MPV), parainfluenza virus (PIV-3) and were significantly more frequent in the first 6 months of life. Clinical severity score of RSV infection was significantly higher than PIV-3 but not for RV or MPV. In multivariate analysis, RV infection was significantly associated with severity while RSV infection was not. Among RSV infections, neither viral load nor viral co-infections were significantly associated with severity. Young age and having fever at admission were significantly associated with both RSV and LRTI severity. A shift in RSV subgroup predominance was observed during two consecutive rainy seasons but was not associated with severity.
  
  
  CONCLUSIONS
  We report etiologies, the epidemiological and clinical characteristics of LRTI among hospitalized children under two years of age and risk factors of RSV and LRTI severity.
authors: Oxford University Clinical Research Unit, Wellcome Trust Major Overseas Program, Ho Chi Minh City, Vietnam.|Murdoch Children's Research Institute, Melbourne, Australia.
authors: Lien Anh Ha
authors: http://orcid.org/0000-0002-2401-8980
authors: LA
authors: Do
authors: Oxford University Clinical Research Unit, Wellcome Trust Major Overseas Program, Ho Chi Minh City, Vietnam.|Nuffield Department of Clinical Medicine, University of Oxford, Oxford, United Kingdom.
authors: Juliet E
authors: JE
authors: Bryant
authors: Children Hospital 1, 341 Su Van Hanh, Ward 10, District 10, Ho Chi Minh City, Vietnam.
authors: Anh Tuan
authors: AT
authors: Tran
authors: Children Hospital 1, 341 Su Van Hanh, Ward 10, District 10, Ho Chi Minh City, Vietnam.
authors: Bach Hue
authors: BH
authors: Nguyen
authors: Children Hospital 2, 14 Ly Tu Trong, Ben Nghe Ward, District 1, Ho Chi Minh City, Vietnam.
authors: Thi Thu Loan
authors: TT
authors: Tran
authors: Children Hospital 2, 14 Ly Tu Trong, Ben Nghe Ward, District 1, Ho Chi Minh City, Vietnam.
authors: Quynh Huong
authors: QH
authors: Tran
authors: Children Hospital 2, 14 Ly Tu Trong, Ben Nghe Ward, District 1, Ho Chi Minh City, Vietnam.
authors: Quoc Bao
authors: QB
authors: Vo
authors: Children Hospital 2, 14 Ly Tu Trong, Ben Nghe Ward, District 1, Ho Chi Minh City, Vietnam.
authors: Nguyen Anh
authors: NA
authors: Tran Dac
authors: Children Hospital 1, 341 Su Van Hanh, Ward 10, District 10, Ho Chi Minh City, Vietnam.
authors: Hong Nhien
authors: HN
authors: Trinh
authors: Children Hospital 1, 341 Su Van Hanh, Ward 10, District 10, Ho Chi Minh City, Vietnam.
authors: Thi Thanh Hai
authors: TT
authors: Nguyen
authors: Children Hospital 1, 341 Su Van Hanh, Ward 10, District 10, Ho Chi Minh City, Vietnam.
authors: Bao Tinh
authors: BT
authors: Le Binh
authors: Children Hospital 1, 341 Su Van Hanh, Ward 10, District 10, Ho Chi Minh City, Vietnam.
authors: Khanh
authors: K
authors: Le
authors: Children Hospital 1, 341 Su Van Hanh, Ward 10, District 10, Ho Chi Minh City, Vietnam.
authors: Minh Tien
authors: MT
authors: Nguyen
authors: Children Hospital 1, 341 Su Van Hanh, Ward 10, District 10, Ho Chi Minh City, Vietnam.
authors: Quang Tung
authors: QT
authors: Thai
authors: Children Hospital 1, 341 Su Van Hanh, Ward 10, District 10, Ho Chi Minh City, Vietnam.
authors: Thanh Vu
authors: TV
authors: Vo
authors: Children Hospital 1, 341 Su Van Hanh, Ward 10, District 10, Ho Chi Minh City, Vietnam.
authors: Ngoc Quang Minh
authors: NQ
authors: Ngo
authors: Children Hospital 2, 14 Ly Tu Trong, Ben Nghe Ward, District 1, Ho Chi Minh City, Vietnam.
authors: Thi Kim Huyen
authors: TK
authors: Dang
authors: Children Hospital 2, 14 Ly Tu Trong, Ben Nghe Ward, District 1, Ho Chi Minh City, Vietnam.
authors: Ngoc Huong
authors: NH
authors: Cao
authors: Children Hospital 2, 14 Ly Tu Trong, Ben Nghe Ward, District 1, Ho Chi Minh City, Vietnam.
authors: Thu Van
authors: TV
authors: Tran
authors: Children Hospital 2, 14 Ly Tu Trong, Ben Nghe Ward, District 1, Ho Chi Minh City, Vietnam.
authors: Lu Viet
authors: LV
authors: Ho
authors: Oxford University Clinical Research Unit, Wellcome Trust Major Overseas Program, Ho Chi Minh City, Vietnam.
authors: Jeremy
authors: J
authors: Farrar
authors: Oxford University Clinical Research Unit, Wellcome Trust Major Overseas Program, Ho Chi Minh City, Vietnam.|Nuffield Department of Clinical Medicine, University of Oxford, Oxford, United Kingdom.|Department of Medical Microbiology, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands.
authors: Menno
authors: M
authors: de Jong
authors: Oxford University Clinical Research Unit, Wellcome Trust Major Overseas Program, Ho Chi Minh City, Vietnam.|Nuffield Department of Clinical Medicine, University of Oxford, Oxford, United Kingdom.
authors: H Rogier
authors: HR
authors: van Doorn
mesh_terms: D002675:Child, Preschool; D006801:Humans; D007223:Infant; D018357:Respiratory Syncytial Virus Infections / Q000453:epidemiology* / Q000209:etiology*; D018113:Respiratory Syncytial Virus, Human / Q000472:pathogenicity; D012141:Respiratory Tract Infections / Q000453:epidemiology* / Q000821:virology*; D012307:Risk Factors; D012621:Seasons; D014744:Vietnam / Q000453:epidemiology; D019562:Viral Load