title: The Dynamic Relationship Between Clinical Symptomatology and Viral Shedding in Naturally Acquired Seasonal and Pandemic Influenza Virus Infections.
abstract: BACKGROUND
  Although the pattern of viral shedding over time has been documented in volunteer challenge studies, understanding of the relationship between clinical symptomatology and viral shedding in naturally acquired influenza infections in humans remains limited.
  
  
  METHODS
  In a community-based study in Hong Kong from 2008 to 2014, we followed up initially healthy individuals and identified 224 secondary cases of natural influenza virus infection in the household setting. We examined the dynamic relationship between patterns of clinical symptomatology and viral shedding as quantified using reverse transcription polymerase chain reaction and viral culture in 127 cases with a clinical picture of acute respiratory infection.
  
  
  RESULTS
  Viral shedding in influenza A virus infections peaked on the first 1-2 days of clinical illness, and decreased gradually to undetectable levels by day 6-7, matching closely with the dynamics of clinical illness. Viral shedding in influenza B virus infections rose up to 2 days prior to symptom onset and persisted for 6-7 days after onset with a bimodal pattern.
  
  
  CONCLUSIONS
  Our results suggest that while clinical illness profiles may serve as a proxy for clinical infectiousness in influenza A virus infections, patients may potentially be infectious even before symptom onset or after clinical improvement in influenza B virus infections.
authors.affiliation: World Health Organization Collaborating Centre for Infectious Disease Epidemiology and Control, School of Public Health, Li Ka Shing Faculty of Medicine, University of Hong Kong, Hong Kong Special Administrative Region, China.
authors.forename: Dennis K M
authors.initials: DKM
authors.lastname: Ip
authors.affiliation: Dalla Lana School of Public Health, University of Toronto, Canada.
authors.forename: Lincoln L H
authors.initials: LLH
authors.lastname: Lau
authors.affiliation: Department of Microbiology.
authors.forename: Kwok-Hung
authors.initials: KH
authors.lastname: Chan
authors.affiliation: World Health Organization Collaborating Centre for Infectious Disease Epidemiology and Control, School of Public Health, Li Ka Shing Faculty of Medicine, University of Hong Kong, Hong Kong Special Administrative Region, China.
authors.forename: Vicky J
authors.initials: VJ
authors.lastname: Fang
authors.affiliation: World Health Organization Collaborating Centre for Infectious Disease Epidemiology and Control, School of Public Health, Li Ka Shing Faculty of Medicine, University of Hong Kong, Hong Kong Special Administrative Region, China.
authors.forename: Gabriel M
authors.initials: GM
authors.lastname: Leung
authors.affiliation: World Health Organization Collaborating Centre for Infectious Disease Epidemiology and Control, School of Public Health, Li Ka Shing Faculty of Medicine, University of Hong Kong, Hong Kong Special Administrative Region, China.|Centre of Influenza Research, Li Ka Shing Faculty of Medicine, University of Hong Kong, Hong Kong Special Administrative Region, China.
authors.forename: Malik J S
authors.initials: MJS
authors.lastname: Peiris
authors.affiliation: World Health Organization Collaborating Centre for Infectious Disease Epidemiology and Control, School of Public Health, Li Ka Shing Faculty of Medicine, University of Hong Kong, Hong Kong Special Administrative Region, China.
authors.forename: Benjamin J
authors.initials: BJ
authors.lastname: Cowling
mesh_terms: D000293:Adolescent; D000328:Adult; D002648:Child; D002675:Child, Preschool; D005260:Female; D006723:Hong Kong; D006801:Humans; D007223:Infant; D009980:Influenza A virus / Q000302:isolation & purification*; D009981:Influenza B virus / Q000302:isolation & purification*; D007251:Influenza, Human / Q000473:pathology* / Q000821:virology*; D008297:Male; D008875:Middle Aged; D060888:Real-Time Polymerase Chain Reaction; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014776:Virus Cultivation; D017201:Virus Shedding; D055815:Young Adult
keywords: influenza; symptoms; viral shedding