Quantifying contributing factors for hospitalization inequalities: influenza and COVID-19, England, 2023 to 2024

Health system decision makers need information on the relative contribution of modifiable contributing factors to inequalities, to develop and prioritise interventions. We used granular linked administrative data to examine ethnic group and deprivation inequalities in hospitalizations for COVID-19 and influenza, England, 2023 to 2024. We used logistic regression to quantify the overall contribution to inequality of multiple contributing factors and estimated the relative contribution of factors which can be influenced by policy: vaccination uptake, pre-existing health conditions and deprivation. Most, but not all, of the excess odds of hospitalization were due to differences between groups in contributing factors considered. For ethnic groups, accounting for vaccination and deprivation made the biggest difference to the excess odds of hospitalization, more so than accounting for a pre-existing health condition. For deprivation, accounting for vaccination made the biggest difference to the excess odds of hospitalization, followed by a pre-existing health condition. Reducing inequalities in vaccination uptake and pre-existing health conditions would reduce hospitalization inequalities; reducing vaccination differences may reduce inequalities the most. For ethnic group inequalities, reducing deprivation inequalities is also vital to reduce hospitalization inequalities.