Influenza B outbreak at an adult cystic fibrosis centre - Clinical impact and factors influencing spread

Jordan B. Dennis, Andrew M. Jones, Emma A. Davies, William Welfare, Peter J. Barry, Lisa Collier, Andrew Turner, Rowland J. Bright-Thomas*

*Corresponding author for this work

    Research output: Contribution to journalArticlepeer-review

    7 Citations (Scopus)


    Introduction: An outbreak of Influenza B occurred at a large United Kingdom (UK) regional adult cystic fibrosis (CF) centre in May 2016. This was late in the UK 2015–2016 influenza season and occurred on a specialist ward with strict infection control procedures. This study investigates the spread of influenza, clinical consequences and potential contributing factors. Methods: Patient records, clinical status and pulmonary function data were reviewed for all inpatients during this period. Respiratory viral PCR results, influenza vaccination status of patients and staff, and environmental factors were also recorded. Affected patients were prospectively monitored for the following three months. Results: 10 of 21 inpatients developed influenza B between 5th and 12th May 2016, an attack rate of 48%. All those characterised were confirmed as the same strain of influenza B/Victoria-lineage. Influenza infection resulted in a mean FEV1 reduction of 10.5% (SD 11.3, p = 0.012), which persisted at 3 months post infection (p = 0.003). Nine of the affected cases rooms were in close proximity on the ward while patients in the two isolation rooms with enhanced ventilation did not become infected. Ventilation measurements in affected rooms ranged from 1.75 to 2.10 air changes/hour, below national recommendations. Seventy percent of affected inpatients had received the 2015/16 trivalent seasonal influenza vaccine, which did not contain a B/Victoria-lineage influenza B virus. Conclusion: This influenza B outbreak in CF adults had a high attack rate and a significant clinical impact. Room ventilation and a limited protection from the seasonal influenza vaccine were possible contributory factors.

    Original languageEnglish
    Pages (from-to)808-814
    Number of pages7
    JournalJournal of Cystic Fibrosis
    Issue number5
    Publication statusPublished - Sept 2020

    Bibliographical note

    Funding Information:
    JD and RBT wrote, edited and prepared the manuscript and figures. JD had full access to all of the data in the study and takes responsibility for the integrity of the data and the accuracy of the data analysis. RBT and AMJ managed the outbreak. PB and LC investigated the outbreak, WW provided public health advice for outbreak, AT provided virology advice during outbreak. AT and ED provided subsequent virology input and analysed national and local viral data. All authors contributed to the manuscript. IRB approval was not required for this study.


    • Cystic fibrosis
    • Influenza
    • Lung function
    • Outbreak
    • Ventilation


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