Impact of CMV Infection and Cancer Treatment on Vaccine Efficacy in Oncology Patients

Cytomegalovirus (CMV) infection leaves lasting effects on the immune system, particularly shaping T-cell populations. In patients with advanced cancer, persistent CMV exposure may influence vaccine responses due to immunosuppression from disease progression or prior therapies. To explore this, we developed CMVision , an open-source ELISpot scoring pipeline that goes beyond traditional spot-forming unit counts, enabling accurate analysis of complex T-cell responses, even in wells with overlapping or ambiguous spots. Using CMVision , we assessed SARS-CoV-2 spike-specific responses after mRNA vaccination in patients with cancer with receiving chemotherapy, immunotherapy or both combined and in cancer-free controls from the VOICE study. CMV-specific responses remained stable across groups. Notably, individuals with stronger CMV-reactivity showed enhanced spike-specific responses, suggesting CMV-memory may reflect immunological “fitness.” These findings position CMVision as a valuable tool and highlight CMV-reactivity as a potential biomarker for vaccine readiness in cancer patients.