What are the guidelines for administering the influenza vaccine to adults, particularly those with chronic health conditions?

Current guidelines for administering the influenza vaccine to adults, particularly those with chronic health conditions, are as follows:

• Adults aged 65 years or over should receive the adjuvanted quadrivalent influenza vaccine (aQIV) or the high-dose quadrivalent influenza vaccine (QIV-HD) as preferred options, with the cell-based quadrivalent influenza vaccine (QIVc) as an alternative.
• Adults aged 18 to 59 years who are eligible should receive QIVc as the preferred vaccine, with QIVe as an alternative.
• Adults with chronic health conditions that increase their risk of serious influenza complications should be offered influenza vaccination. These conditions include chronic respiratory diseases (such as asthma requiring steroids or previous hospital admissions, COPD, bronchiectasis), chronic heart disease, chronic kidney disease (stage 3 or above), chronic liver disease, chronic neurological diseases (including Parkinson’s disease, motor neurone disease, multiple sclerosis, dementia, cerebral palsy, severe learning disabilities), diabetes (type 1, type 2 requiring medication, or diet-controlled), adrenal insufficiency, immunosuppression (due to disease or treatment including chemotherapy, radiotherapy, HIV at all stages, transplant recipients, haematological malignancies, and those on immunosuppressive therapies), asplenia or splenic dysfunction (including sickle cell disease and coeliac disease), and morbid obesity (BMI ≥40 kg/m2).
• Vaccination should also be offered to household contacts of immunocompromised individuals and carers of vulnerable people.
• Influenza vaccine should not be given to people with a confirmed anaphylactic reaction to a previous dose or any component of the vaccine (except ovalbumin in some cases), or to those who are acutely unwell with a febrile illness; vaccination should be postponed until recovery.
• Fluenz nasal spray is contraindicated in severely immunocompromised children and young people, those with severe egg allergy requiring intensive care, and those on systemic salicylate therapy.

These recommendations are based on the UK Health Security Agency's 'Green Book' chapter on influenza and the National flu immunisation programme plan 2024 to 2025.