BTK and B-cell chronic lymphocytic leukemia: Considering previous studies in CLL patients receiving Bruton’s tyrosine kinase (BTK) inhibitors [31,32], CD4+ T lymphocytes could exhibit increased reactivity to new antigens such as SARS-CoV peptides because these drugs can restore TCR repertoire diversity and alter the composition of T-lymphocyte subtypes by exerting selective Th1 pressure.