Antibody Persistence after Third Dose of BNT162b2 mRNA COVID-19 Vaccination in Serongative Patients with Chronic Lymphocytic Leukemia;Change in the number of participants with BNT162b2 mRNA vaccine-related adverse events as assessed by a questionnaire relating to the development of patients' side effects to the vaccine, which was developed by study investigators.

Antibody Persistence after Third Dose of BNT162b2 mRNA COVID-19 Vaccination in Serongative Patients with Chronic Lymphocytic Leukemia;Change in the number of participants with BNT162b2 mRNA vaccine-related adverse events as assessed by a questionnaire relating to the development of patients' side effects to the vaccine, which was developed by study investigators.

Change in the number of participants with BNT162b2 mRNA vaccine-related adverse events as assessed by a questionnaire relating to the development of patients' side effects to the vaccine, which was developed by study investigators.

Change in the number of participants with BNT162b2 mRNA vaccine-related adverse events as assessed by a questionnaire relating to the development of patients' side effects to the vaccine, which was developed by study investigators.