In-depth cellular and humoral dynamics of the response to COVID-19 vaccine booster in patients with chronic B-cell neoplasms

While the development of SARS-CoV-2 vaccines offers substantial protection against COVID-19 illness in the general population, impaired antibody responses are present in patients with mature B-cell neoplasms, including chronic lymphocytic leukemia (CLL) [ 1 ]. This is the case regardless of treatment status, although B-cell targeting agents, such as anti-CD20 mAb and BTK inhibitor therapy, further inhibit antibody responses [ 2 , 3 ]. Despite this, antibody responses may improve with repeated vaccinations [ 4 , 5 ]. By contrast, data regarding T-cell responses in these patients is less clear. Vaccine-induced memory T cells are essential for providing help to B cells for antibody production, as well as aiding in viral clearance upon subsequent exposure. Several studies of vaccinated patients with hematologic malignancies have reported the presence of virus-specific T cells, even in the absence of a humoral response [ 6 , 7 , 8 ]. Such T cells harbor or secrete IFN-γ and, similar to antibodies, T-cell responses may be boosted with repeated vaccinations [ 4 , 5 , 8 , 9 ].