Influenza Autumn Winter 2025 campaign: Cohort identification methodology

The NHS England Vaccination programme commissioned NHS England Vaccine Digital Services to make patient identifiable data available to their Data Processing Service.

This data is to be used within the Influenza Autumn Winter 2025 campaign for:

• call and recall
• reporting
• monitoring purposes

NHS England Vaccination Programme commissioned NHS England Cohorting as a Service (CaaS) to provide patient identifiable cohorts for the identification of citizens who are eligible for influenza vaccinations for the autumn and winter 2025 season as outlined in table 19.4 of Chapter 19 of the Green Book (PDF, 598KB).

A patient cohort has been created and made available in NHS England’s Cohort Processing System to enable the national call and recall process.

Chapter 19 of the Green Book identifies 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 criteria are:

• 2 to 3 years of age on 31 August 2025
• 4 to 16 years of age on 31 August 2025
• 65 years of age and over on 31 March 2026

This document outlines NHS England’s Cohorting as a Service's approach to delivering this cohort using established methodologies.

The 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 of Chapter 19 of the Green Book (PDF, 598KB).

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

The code set used within the GPES and GDPPR data sets is:

• SNOMED CT: Systematized Nomenclature of Medicine