Pneumococcal vaccination uptake in people with immunosuppressed conditions using real-world primary care data across England: Protocol for a retrospective descriptive study (Preprint)

BACKGROUND The introduction of pneumococcal vaccination programmes in the UK has led to substantial reduction in the burden of pneumococcal disease in the general population, decreasing the incidence of invasive pneumococcal disease (IPD) and preventing associated mortality. OBJECTIVE We aim to evaluate the yearly uptake of pneumococcal vaccine in adults who are included in national recommendations as people with immunosuppressive conditions, stratified by aetiology of immunosuppression. METHODS This will be a retrospective cohort study with data from the Oxford-Royal College of General Practitioners (RCGP) Research and Surveillance Centre (RSC) network, which is nationally representative of the English population. The population are adults registered in the RSC database with immunosuppression, including those with bone marrow compromise, solid organ transplant, receiving oncological treatment, using immunosuppressive drugs, or with primary or acquired immunodeficiencies. The exposure is the underlying medical condition leading to an immunosuppression category. The primary outcome will be pneumococcal vaccination, defined as one dose of PPV23. Vaccination rates will be calculated using the number of vaccinated people in high-risk groups as the numerator and estimates of the total high-risk population in the RSC dataset as the denominator. We will compare amongst vaccinated and unvaccinated people, and across immunosuppressive aetiologies using descriptive statistics, with pairwise comparisons using standardized mean differences. RESULTS We will report pneumococcal vaccine uptake disaggregated for the high-risk group of people with immunosuppressive conditions, which have not been previously reported. We will report on the socioeconomic gradient for vaccine uptake, through the use of the index of multiple deprivation score and region; report on the differences amongst ethnic groups; and report on vaccination uptake during the COVID-19 pandemic period. We will curate an ontology for immunosuppressive conditions, contributing to CMR research following the open science frameworks for reproducible research. CONCLUSIONS We will inform on the granularity of routine primary care data to include disaggregated reports of vaccine uptake in the immunosuppressed population in routine surveillance in the UK. This will aim to address the gap on pneumococcal vaccination coverage in people with immunosuppressive conditions, helping to identify potential unwarranted variations in vaccine adoption.