OBJECTIVES: As of 05/27/21, 50.5% of the United States population had initiated COVID-19 vaccination. Vaccination rates, safety and efficacy among those on active chemotherapy are not well published. As a first step towards improving cancer patient care, we explored vaccination rates among patients on active chemotherapy to gain insights on its utilization in this population and improve care of cancer patients. METHODS: On 01/23/21, McKesson Specialty Health deployed a COVID Vaccine Administration survey within its iKnowMed electronic health record platform. Cancer patients who answered the survey with ongoing chemotherapy 30 days prior to or after 01/01/21 and ≥2 office visits between 01/01/21 and 05/27/21 were included in the study. Self-reported and onsite vaccination, brand, and COVID-19–related information were recorded. Chi-squared tests were used to determine significant differences between groups. RESULTS: Selection criteria yielded 50,423 patients. The study population was 55% female (n=27,923) with a median age of 68 years (min, max 20, 80+). Approximately 60% (n=11,867) reported initiating vaccination, and 40% (n=7,797) reported being fully vaccinated. The majority of patients reported having received the vaccine by Pfizer (52%, n=10,275), followed by Moderna (45%, n=8,836), Janssen (3%, n=540), and AstraZeneca <1%. Vaccination rates did not differ significantly between females (39%, n=10,799) and males (39%, n=8,865). Patients aged ≤69 years had a significantly lower rate than those older (34%, n=8,928 vs 44%, n=10,736; p<0.0001). Patients with metastatic disease had a significantly higher vaccination rate than those without metastasis (40%, n=14,591 vs. 36%, n=5,073; p<0.0001). CONCLUSIONS: This study marks an initial review of the first 6 months post emergency use authorization of COVID-19 vaccinations. The survey responses could not be validated with external data sources. Continued research is needed to investigate reasons for lower rates, adverse effects, and treatment selection, and to monitor patient outcomes amongst vaccinated patients on chemotherapy.