• Open Access

Virus detection and its association with symptoms during influenza-like illness in a sample of healthy adults enrolled in a randomised controlled vaccine trial

Authors

  • Peter F. Howard,

    1. Murdoch Children’s Research Institute & Melbourne School of Population Health, The University of Melbourne, Parkville, Vic., Australia
    Search for more papers by this author
    • These authors contributed equally to this work.

  • James M. McCaw,

    1. Murdoch Children’s Research Institute & Melbourne School of Population Health, The University of Melbourne, Parkville, Vic., Australia
    Search for more papers by this author
    • These authors contributed equally to this work.

  • Peter C. Richmond,

    1. University of Western Australia, School of Paediatrics and Child Health & Telethon Institute for Child Health Research, Princess Margaret Hospital for Children, Perth, WA, Australia
    Search for more papers by this author
  • Michael Nissen,

    1. Queensland Paediatric Infectious Diseases Laboratory, Queensland Children’s Medical Research Institute and Sir Albert Sakzewski Virus Research Centre, Queensland Children’s Health Services, The University of Queensland, Brisbane, Qld, Australia
    Search for more papers by this author
  • Theo Sloots,

    1. Queensland Paediatric Infectious Diseases Laboratory, Queensland Children’s Medical Research Institute and Sir Albert Sakzewski Virus Research Centre, Queensland Children’s Health Services, The University of Queensland, Brisbane, Qld, Australia
    Search for more papers by this author
  • Stephen B. Lambert,

    1. Queensland Paediatric Infectious Diseases Laboratory, Queensland Children’s Medical Research Institute and Sir Albert Sakzewski Virus Research Centre, Queensland Children’s Health Services, The University of Queensland, Brisbane, Qld, Australia
    Search for more papers by this author
  • Michael Lai,

    1. Clinical Research and Development, CSL Limited, Parkville, Vic., Australia.
    Search for more papers by this author
  • Michael Greenberg,

    1. Clinical Research and Development, CSL Limited, Parkville, Vic., Australia.
    Search for more papers by this author
  • Terry Nolan,

    1. Murdoch Children’s Research Institute & Melbourne School of Population Health, The University of Melbourne, Parkville, Vic., Australia
    Search for more papers by this author
  • Jodie McVernon

    1. Murdoch Children’s Research Institute & Melbourne School of Population Health, The University of Melbourne, Parkville, Vic., Australia
    Search for more papers by this author

James McCaw, Vaccine and Immunisation Research Group, Melbourne School of Population Health and Murdoch Childrens Research Institute, The University of Melbourne, Parkville, Vic. 3010, Australia. E-mail: jamesm@unimelb.edu.au

Abstract

Background  Viral respiratory infections are associated with significant morbidity and mortality. Many new aetiological agents have been described recently.

Objectives  We looked for respiratory viruses in a population-based sample of healthy adults with influenza-like illness (ILI). We investigated host and spatio-temporal associations with virus isolation and host, spatio-temporal and virus associations with self-reported symptoms.

Patients/Methods  We recruited 586 participants experiencing 651 illness episodes from a population of healthy adults enrolled in an influenza vaccine effectiveness trial. At ILI assessment visits, a respiratory swab was collected and tested for viruses using a combination of polymerase chain reaction (PCR) assays. Participants also completed a questionnaire detailing their clinical course in 336 episodes.

Results  Of 643 samples analysed, a virus was identified in 44%. Half were picornaviruses, with influenza and coronaviruses the next most common. Individuals with influenza were significantly less likely to have been immunised than the reference (virus negative) population (OR = 0·52 (0·31, 0·87) = 0·01).

The mean symptom score (95% CI) reported by individuals with influenza was significantly higher than in all other episodes [Influenza: 10·2 (9·4, 10·9); Other: 7·4 (7·2, 7·7); Difference (95% CI): 2·5 (1·5, 3·5); < 0·001]. In an analysis restricted to influenza-positive cases, the symptom score was not attenuated by vaccination.

Conclusions  Our findings indicate that a greater number of symptoms are displayed by individuals presenting with influenza confirmed ILI compared with other agents that cause ILI. While influenza vaccination reduced the probability of influenza virus detection, symptom score for influenza-positive ILI was not attenuated.

Ancillary