Chronic lymphocytic leukemia (CLL) is the most common adult leukemia and typically affects older patients, often with co-morbidities. As CLL patients have impaired immune systems and can have varied responses to vaccinations, they have traditionally been excluded from vaccine trials, including many of the ongoing COVID-19 studies. This research project aims to evaluate the efficacy of the COVID-19 vaccine in patients with CLL. Patients’ immune status will be evaluated pre- and post-vaccination to assess the vaccine’s success in stimulating an effective immune response. These findings will also assist physicians as they educate CLL patients about the ongoing need for safety precautions to avoid COVID-19.