Background <p>Solid organ transplant recipients were among the most vulnerable groups during the COVID-19 pandemic. Chronic immunosuppression and multiple comorbidities greatly increase the risk of severe illness and death. Despite global advances in vaccination and treatment, practical tools for early risk assessment in this group are still limited. This study aims to address this gap by identifying simple, widely available laboratory markers that can be used upon hospital admission to predict short-term outcomes in COVID-19 patients with a history of organ transplantation.</p> Methods <p>We retrospectively analyzed a cohort of solid organ transplant recipients hospitalized with confirmed COVID-19 infection at the University Clinical Center in Gdańsk, Poland, between 2020 and 2022. Patients were admitted to either a general COVID-19 ward or an intensive care unit based on disease severity. Data were collected from electronic medical records and included demographic characteristics, chest imaging, and routine laboratory tests: lymphocyte count, serum creatinine, aspartate aminotransferase, C-reactive protein, and procalcitonin. Statistical analyses were performed to evaluate the association of these variables with in-hospital mortality.</p> Results <p>Our analysis identified that elevated levels of serum creatinine, aspartate aminotransferase, C-reactive protein, and procalcitonin were significantly associated with increased risk of in-hospital mortality. Conversely, a higher lymphocyte count at admission was associated with better survival. These markers are widely available, inexpensive, and can be assessed during the initial diagnostic workup.</p> Conclusions <p>This study offers a practical, evidence-based approach to early risk stratification in transplant recipients with COVID-19. The identified laboratory markers are not only simple and accessible but also clinically meaningful, providing frontline clinicians with actionable information during the early stages of care. In light of the continued presence of COVID-19 and the likelihood of future viral outbreaks, these findings have broad implications for the management of immunosuppressed patients. The study provides valuable insights into a currently underserved area of transplant medicine and has strong potential to inform clinical practice across diverse healthcare settings.</p> Trial registration <p>Not applicable.</p>