Sepsis is a life-threatening organ dysfunction resulting from dysregulated immune responses to infection, affecting almost 50 million people yearly. Sepsis is a major global health challenge and a leading cause of death worldwide. Moreover, people surviving sepsis often suffer post-sepsis immunosuppression, a long-lasting state of immune dysfunction predisposing them to infections, autoimmune and non-communicable diseases (NCDs), and long-term reduced fitness. The molecular mechanisms driving post-sepsis immunosuppression remain largely elusive. Furthermore, predicting which patients will survive or develop immunosuppression is currently impossible. BEATsep will tackle this challenge by combining the expertise of physicians, clinician scientists and immunologists in top European institutions. We will, for the first time, longitudinally assess unique immunological and clinical parameters and combine them to: i) gain insight into the long-term immunological consequences of septic shock; ii) identify novel markers to identify patients at risk; and iii) unravel molecular mechanisms driving post-sepsis immunosuppression. We will also develop strategies to improve the stratification of acute sepsis survivors to identify patients with a higher risk of sepsis-associated NCDs and comorbidities. BEATsep will have significant societal, scientific, and economic impacts, as efficient prevention of sepsis-induced comorbidities could save significant amounts within healthcare budgets and potentially improve the quality of life for millions worldwide who suffer from the long-term effects of sepsis.