Dr. Susan Leclair has reviewed three abstracts from the 2021 American Society of Hematology Annual Meeting and Exposition, or ASH 2021, on chronic lymphocytic leukemia/small lymphocytic lymphoma (CLL / SLL) patients’ responses to vaccines, two on the COVID-19 vaccine, and one on the shingles vaccines. These trials include data on both antibodies (humeral) and T cell (cellular) responses. We suggest reading all three articles together as Dr. Leclair explains some of the nuances of the impairment of immunity in CLL / SLL in her discussion across all three articles.