Immune Response to SARS-CoV-2 (COVID-19) Vaccines in Patients With Chronic Lymphocytic Leukemia or Small Lymphocytic Lymphoma

OUTLINE: For patients who have not been vaccinated at the time of enrollment, they will undergo collection of blood samples prior to the first vaccine dose, just before the second vaccine dose, and then at 1, 6, and 12 months after the second vaccine dose. Patients' medical records are also reviewed. For patients enrolled after vaccination, they will undergo collection of blood samples at 1-4, 6, and 12 months after completing the vaccination series. Patients who receive booster dose also undergo collection of blood samples at 1, 6, and 12 months post final booster dose. After completion of study, patients are followed up every 6 months for 2 years.