title: The burden of single virus and viral coinfections on severe lower respiratory tract infections among preterm infants: a prospective birth cohort study in Brazil.
abstract: BACKGROUND
  Respiratory syncytial virus (RSV) is associated with severe lower respiratory tract infection (LRTI), especially in preterm infants. Other viruses, co-detected with RSV, may play a role in the severity of respiratory outcomes.
  
  
  METHODS
  This prospective epidemiologic study of severe LRTI incidence among children born ≤35 weeks gestational age at 3 sites in Brazil (2008-2010) followed a birth cohort for 1 year post-enrollment. Nasal washes from subjects with LRTI were tested for respiratory viruses using polymerase chain reaction. The primary outcome was the incidence of severe LRTI requiring hospitalization associated with RSV infection. Secondary outcomes included identification of viruses associated with LRTI, alone or coinfections, and risk factors associated with severe LRTI.
  
  
  RESULTS
  Among 303 subjects, 176 (58.1%) experienced LRTI. Among these subjects, 162 had samples tested using polymerase chain reaction; 27.8% (45/162) experienced severe LRTI. More subjects with severe LRTI were infected with RSV (30/45, 66.7%) than with other viruses. RSV was present in 33.1% (143/432) of LRTI events tested, 57.3% (82/143) were coinfections. RSV was the virus most frequently associated with severe LRTIs (34/56 events, 60.7%); 50% (17/34 events) single and 50% coinfections. Significantly longer hospital stays were associated with LRTI events involving RSV coinfections compared with RSV single infections (P = 0.012). Infants with severe LRTIs had significantly lower mean RSV-IgG levels at study entry compared with those with nonsevere or no LRTIs (P < 0.05).
  
  
  CONCLUSIONS
  This study confirms the association of RSV alone or as a coinfection with severe LRTI and reinforces the importance of providing adequate prophylaxis for susceptible infants.
authors.affiliation: From the *University of São Paulo, School of Medicine, Cell Biology Department, Ribeirão Preto; †Pontifícia Universidade Católica do Rio Grande do Sul, School of Medicine, Infant Center, Biomedical Research Institute, Porto Alegre; ‡Federal University of Paraná, School of Medicine, Department of Pediatrics, Curitiba, Brazil; §AbbVie Inc., Medical Affairs, Virology, Buenos Aires, Argentina; ¶AbbVie Inc., Virology Global Project Team, Global Pharmaceutical Research and Development (GFN) and Global HEOR (PV), North Chicago, IL; and ‖Abbott Brazil, Medical Affairs, São Paulo, Brazil.
authors.forename: Eurico
authors.initials: E
authors.lastname: Arruda
authors.forename: Marcus H
authors.initials: MH
authors.lastname: Jones
authors.forename: Flavia
authors.initials: F
authors.lastname: Escremim de Paula
authors.forename: Debora
authors.initials: D
authors.lastname: Chong
authors.forename: Gabriela
authors.initials: G
authors.lastname: Bugarin
authors.forename: Gerard
authors.initials: G
authors.lastname: Notario
authors.forename: Alessandra K
authors.initials: AK
authors.lastname: Matsuno
authors.forename: Paulo M
authors.initials: PM
authors.lastname: Pitrez
authors.forename: Pamela
authors.initials: P
authors.lastname: Vo
authors.forename: Claudia
authors.initials: C
authors.lastname: Suzuki
authors.forename: Nelson
authors.initials: N
authors.lastname: Rosario Filho
authors.forename: Renato T
authors.initials: RT
authors.lastname: Stein
mesh_terms: D001938:Brazil / Q000453:epidemiology; D060085:Coinfection / Q000453:epidemiology* / Q000821:virology; D016021:Epidemiologic Studies; D005260:Female; D006801:Humans; D015994:Incidence; D007223:Infant; D007231:Infant, Newborn; D007234:Infant, Premature; D008297:Male; D011446:Prospective Studies; D018357:Respiratory Syncytial Virus Infections / Q000150:complications* / Q000453:epidemiology*; D012141:Respiratory Tract Infections / Q000453:epidemiology*; D014780:Viruses / Q000145:classification / Q000302:isolation & purification*