T-cell immune response after mRNA SARS-CoV-2 vaccines is frequently detected also in the absence of seroconversion in patients with lymphoid malignancies

Patients affected by lymphoid malignancies (LM) are frequently immune-compromised, suffering increased mortality from COVID-19. This prospective study evaluated serological and T-cell responses after complete mRNA vaccination in 263 patients affected by chronic lymphocytic leukaemia, B- and T-cell lymphomas and multiple myeloma. Results were compared with those of 167 healthy subjects matched for age and sex. Overall, patient seroconversion rate was 64 center dot 6%: serological response was lower in those receiving anti-cancer treatments in the 12 months before vaccination: 55% vs 81 center dot 9% (P < 0 center dot 001). Anti-CD20 antibody plus chemotherapy treatment was associated with the lowest seroconversion rate: 17 center dot 6% vs. 71 center dot 2% (P < 0 center dot 001). In the multivariate analysis conducted in the subgroup of patients on active treatment, independent predictors for seroconversion were: anti-CD20 treatment (P < 0 center dot 001), aggressive B-cell lymphoma diagnosis (P = 0 center dot 002), and immunoglobulin M levels <40 mg/dl (P = 0 center dot 030). The T-cell response was evaluated in 99 patients and detected in 85 of them (86%). Of note, 74% of seronegative patients had a T-cell response, but both cellular and humoral responses were absent in 13 center dot 1% of cases. Our findings raise some concerns about the protection that patients with LM, particularly those receiving anti-CD20 antibodies, may gain from vaccination. These patients should strictly maintain all the protective measures.