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

Guidelines for administering the seasonal 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, including those with chronic health conditions, should be offered QIVc as the preferred vaccine, with the egg-based quadrivalent influenza vaccine (QIVe) as an alternative.
• Adults with chronic health conditions that increase their risk of serious influenza complications include those with chronic respiratory disease (e.g., asthma requiring steroids or previous hospital admissions), chronic heart disease, chronic kidney disease (stage 3 or above), chronic liver disease, chronic neurological diseases (such as Parkinson’s disease, motor neurone disease, multiple sclerosis, dementia), diabetes (type 1, type 2 requiring medication, or diet-controlled), adrenal insufficiency, immunosuppression (due to disease or treatment), asplenia or splenic dysfunction, and morbid obesity (BMI ≥40 kg/m2).
• Vaccination should be offered to these clinical risk groups regardless of age, based on individual assessment and clinical judgement.
• Influenza vaccine should not be given to individuals with a confirmed anaphylactic reaction to a previous dose of the vaccine or any of its components (except ovalbumin in some cases), and vaccination should be postponed in those who are acutely unwell with febrile illness until recovery.
• For people with suspected or confirmed anaphylaxis to vaccine excipients, vaccine formulations free of the identified excipients should be used.
• Some immunocompromised patients may have a suboptimal immune response but should still be vaccinated.
• Vaccination should also be offered to household contacts of immunocompromised individuals to reduce transmission risk.

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, as well as NICE guidance on flu vaccination uptake ¹,²,³.