Investigating the human - human transmission of influenza

If an influenza pandemic occurs, between one quarter and one third of the entire population are expected to become ill at some point. Everyone will need to work together to reduce and slow the spread of the virus by taking simple hygiene precautions such as hand washing and household cleaning. At the moment we do not know how effective these hygiene measures will be or whether the public will use them. Also, we don‘t know enough about how influenza is spread and whether face masks will be useful to members of the public in certain situations. We will perform a clinical trial using volunteers; some will be asked to do things like wash their hands or wear a mask when someone in the household gets a respiratory infection (like a common cold). We will also assess how easy it is to follow this advice. The results will allow the government to give sensible advice to families, based on real evidence, when a pandemic comes. The research will be carried out by teams based at Nottingham University and University College London.

Aims: To assess whether non-pharmaceutical countermeasures applied within households can reduce household secondary attack rates of acute respiratory infections (ARI) in winter.

Objectives: In the event of an influenza pandemic, authoritative advice on infection control will be necessary across a wide range of settings from healthcare to general household. The evidence base for non-pharmaceutical interventions to reduce the transmission of ARIs is weak but in the context of pandemic influenza such interventions could prove to be extremely important. On the background of a study called Flu Watch (a community study of behavioural and biologic determinants of Influenza-like illness), a study will evaluate interventions to reduce the transmission of ARIs within households.

Design: This will be a cluster-randomised, single blinded, intervention study. The investigator will be blind to the randomisation of household to specific interventions. The study will use epidemiological and clinical trial methodologies, and relevant univariable and multivariable statistical analyses.

Methods: A pilot study will trial the use of hand hygiene education and techniques (e.g. alcohol gels), surface decontamination protocols, and the use of face masks for both the symptomatic subject and other household members. It will explore the most practical and achievable interventions which families find acceptable and which policy makers are likely to consider practical and allow the development of appropriate and robust data collection methods.
This will be followed by a clinical trial over the next two winter seasons. A community cohort of households in England will be recruited from the MRC General Practice Research Framework. The 4 main arms will be: control (no intervention) vs intervention aimed at contact transmission (hand and surface cleansing) vs interventions aimed at large droplet transmission (masks and social distancing) vs both interventions combined.
Detailed data collection methods including use of illness diaries and automated telephone-based real-time illness reporting will allow measurements of compliance and effectiveness. A specific problem in such studies is participant compliance with the interventions. This will be addressed by the use of a pilot study to refine the nature of the interventions used and optimise acceptability.

Opportunities: This project provides the chance to construct pragmatic and effective infection control advice that is evidence based. Studies assessing the impact of multiple interventions have not been done before. It will be used to inform pandemic influenza preparedness planning but could also measure the impact of reduced transmission of ARI on sick leave (work or school) outside of a pandemic.