CD4 and B-cell chronic lymphocytic leukemia: spike‐specific CD4+ T‐cell responses were investigated in a number of immunocompromised patients, including those with solid organ transplants (n = 41), hematopoietic stem cell transplants (n = 43), chronic lymphocytic leukemia (n = 53), primary immunodeficiency (n = 48) and HIV infection (n = 50).63