This proposal represents a unified programme supported by both clinical and academic staff in the Departments of Paediatrics at Imperial College and St Mary's Hospital, Southampton Hospital and John Radcliffe Hospital (Oxford). St Mary's Hospital is the hub of a paediatric network for West London, and forms part of the Paediatric Intensive Care Network for the London region, with potential access to a population of 3 million children.

We aim to improve diagnosis and understanding of children with infectious, inflammatory and allergic conditions. Our study will establish well-characterised cohorts of patients with defined conditions, in whom microbiological and patient samples will be used to understand the contribution of genetic background, differential gene expression, proteomics and the pathogen type to the disease process.

Unwell children coming to hospital through any route will be invited to join the study. Entering the study will entail the child having blood taken for research purposes in addition to the clinically indicated tests. We will also recruit well (control) children who are having blood tests performed for elective purposes, such as surgery.

In addition, children presenting with an illness that is likely to have an infectious aetiology will also have samples collected for microbiological diagnosis. Those samples taken for ordinary diagnostic purposes (such as blood, urine, cerebrospinal fluid (CSF), bronchoalveolar lavage (BAL) fluid or nasal brushings for epithelial cell cultures) would also be used for state-of-the-art diagnostic techniques, in order to maximise the likelihood of confirming a microbiological diagnosis. Where healthy, uninfected children are having invasive procedures, such as lumbar punctures, we would aim to recruit these children as controls and collect biological samples such as CSF samples.

This bid addresses the need for translational research in paediatrics, by building on the world-class basic science and clinical paediatric base at Imperial College and St Mary's Hospital.

There is currently little understanding of the mechanisms by which respiratory infections can cause severe illness and death. The emergence of Influenza A subtype (H1N1) as a major cause of childhood severe illness in 2009 permitted further study of how this virus triggers severe disease, and how the inflammatory response to H1N1 differs from other infections. It is likely that host-mediated inflammatory processes triggered by the infecting agent contributes to severe illness. In addition, viral infection induces profound changes in the innate immune response to common bacterial pathogens, with increased bacterial colonisation of normally sterile lower airway. Thus both host and bacterial factors may contribute to lung damage in severe respiratory infection.

This study was initiated to identify the aetiology and immunopathologic mechanisms of childhood respiratory infection (Immunopathology of Respiratory Infection Study - IRIS), recruiting children with suspected respiratory infection or respiratory failure (and controls). This dataset will provide a unique resource for further study of disease mechanisms in children with a range of infections including H1N1/09 infection, Respiratory Syncytial Virus (RSV), Rhinovirus, other common respiratory viruses and severe bacterial infections.

Inclusion Criteria:

• children presenting via any means to Hospital
• children needing blood tests for any clinical reason
• children who have presented because of a condition consistent with an infectious, inflammatory or allergic process

Exclusion Criteria:

• aged 17 or older
• children re-presenting with the same condition
• concern that the study is not fully understood by the parent or guardian

Unwell children coming to St Mary's Hospital, Southampton Hospital or John Radcliffe Hospital (Oxford) through any route (Emergency Department, wards, intensive care)

Participants were monitored for all-cause mortality throughout their stay in hospital, and received follow-up review at 10 days if they survived to discharge.

No adverse event data were collected apart from all cause mortality data