Contributors This version of the guidance was reviewed and agreed in Summer 2015, by a working group comprising: Maria Zambon, Deputy Director, National Infections Service, Public Health England Richard Pebody, Interim Head of Respiratory Diseases Department, National Infections Service, Public Health England Gavin Dabrera, Interim Head of Influenza Preparedness and Response, Respiratory Diseases Department, Public Health England Paul Cleary, Consultant Epidemiologist, National Infections Service, Public Health England Joanna Ellis, Clinical Scientist, National Infections Service, Public Health England Frances Parry-Ford, Respiratory Diseases Scientist, National Infections Service, Public Health England Matthew Donati, Consultant Medical Virologist, Public Health England Bristol Public Health Laboratory and University Hospitals Trust Bristol NHS Foundation Trust Meera Chand, Consultant Medical Microbiologist, Public Health England and Guy’s & St Thomas’ NHS Foundation Trust Philip Howard, Consultant Antimicrobial Pharmacist, Leeds Teaching Hospitals NHS Trust Mark Borthwick, Consultant Pharmacist, John Radcliffe Hospital Arlene Reynolds, Senior Epidemiologist, Health Protection Scotland We would like to acknowledge the contributions of: Jim McMenamin, Consultant Epidemiologist, Health Protection Scotland Bryan O’Farrell, Senior Critical Care Specialist, Royal Free Hospital Steve Tomlin, Consultant Pharmacist, Children’s Services, St Thomas’ Hospital Rob Shulman, Lead Critical Care Pharmacist, University College London Hospital Sarah Lock, Consultant in Communicable Disease Control, Public Health England
Definitions 1. Uncomplicated influenza: influenza presenting with fever, coryza, generalised symptoms (headache, malaise, myalgia, arthralgia) and sometimes gastrointestinal symptoms, but without any features of complicated influenza. 2. Complicated influenza: influenza requiring hospital admission and/or with symptoms and signs of lower respiratory tract infection (hypoxaemia, dyspnoea, lung infiltrate), central nervous system involvement and/or a significant exacerbation of an underlying medical condition. 3. Risk factors for complicated influenza:  chronic neurological, hepatic, renal, pulmonary and chronic cardiac disease  diabetes mellitus  severe immunosuppression  age over 65 years  pregnancy (including up to two weeks post partum)  children under six months of age  morbid obesity (BMI ≥40) For full details refer to ‘Immunisation against infectious disease’, known as the Green Book (4). 4. Severe immunosuppression: Examples of severe immunosuppression relevant to this guidance are given below. Degrees of immunosuppression are difficult to quantify and individual variation exists, therefore this list is not comprehensive:  severe primary immunodeficiency  current or recent (within six months) chemotherapy or radiotherapy for malignancy  solid organ transplant recipients on immunosuppressive therapy  bone marrow transplant recipients currently receiving immunosuppressive treatment, or who received it within the last 12 months  patients with current graft-versus-host disease  patients currently receiving high dose systemic corticosteroids (equivalent to ≥40 mg prednisolone per day for >1 week in an adult, or ≥ 2mg/kg/day for ≥1 week in a child), and for at least three months after treatment has stopped  HIV infected patients with severe immunosuppression (CD4<200/μl or <15% of total lymphocytes in an adult or child over five; CD4< 500/μl or <15% of total lymphocytes in a child aged one to five; expert clinical opinion in a child aged under one)  patients currently or recently (within six months) on other types of immunosuppressive therapy or where the patient’s specialist regards them as severely immunosuppressed