Influenza vaccinations 2024-25: Cohort identification methodology

NHS England's Vaccination and Screening directorate has commissioned the NHS England Vaccine Digital Service (VDS) to flow patient identifiable data to be used for influenza vaccine monitoring and call/recall within the 2024 to 2025 flu season that runs from 1 September 2024 to 31 March 2025.

NHS England’s Vaccination programme has commissioned NHS England’s Cohorting as a Service (CaaS) to provide patient identifiable cohorts to facilitate the identification of citizens who are eligible for influenza vaccinations for the autumn and winter 2024 to 2025 season under the Green Book chapter 19 clinical and other at risk criteria.

The clinical at-risk groups within the Green Book are: 

• chronic respiratory disease
• chronic heart disease and vascular disease 
• chronic kidney disease
• chronic liver disease
• chronic neurological disease
• diabetes and adrenal insufficiency
• immunosuppression
• morbid obesity (class 3 obesity)
• asplenia or dysfunction of the spleen
• pregnant women

Age based cohorting: 

• 2 to 3 years of age on 31 August 2024
• 4 to 16 years of age on 31 August 2024
• 65 years of age and over on 31 March 2025

This document outlines NHS England’s Cohorting as a Service's approach to deliver this cohort using established methodologies. It also highlights any divergence from the clinical criteria held within Chapter 19 of the Green Book and associated assumptions.

Data sets used are:

• GPES (General Practice Extraction Service) v5
• Personal Demographics Service

All those aged 6 months or older in the clinical risk groups shown in Table 19.4, Chapter 19 of the Green Book.

All those in the age-based cohorts outlined in the overview section.

The code set used within the GPES data sets is:

• SNOMED CT: Systemized Nomenclature of Medicine