This national retrospective cohort study examined the risk of COVID-19 death among adults aged 50-100 in England who received a booster vaccination in autumn 2022. Using data from the 2021 Census linked to electronic health records, the study found that several pre-existing health conditions were associated with an increased risk of COVID-19 death, even after receiving a booster. These conditions included learning disabilities or Down Syndrome, pulmonary hypertension or fibrosis, motor neuron disease, multiple sclerosis, myasthenia gravis or Huntington’s disease, cancer of blood and bone marrow, Parkinson’s disease, and liver cirrhosis. The study highlights the continued vulnerability of certain groups and emphasizes the need for prioritizing these individuals for subsequent booster doses.