Seroconversion rates following COVID-19 vaccination amongst patients with malignant disease- the impact of diagnosis and cancer-directed therapies

As COVID-19 has been shown to adversely affect patients with cancer, prophylactic strategies are critically needed. We determined the immunogenicity of COVID-19 vaccination in a cohort of cancer patients that had received full dosing with one of the FDA-approved COVID-19 vaccines. 201 oncology patients underwent anti-spike protein SARS-CoV-2 IgG testing post-vaccination and demonstrated a high rate of seroconversion (94%) overall. When compared to solid tumors (98%), a significantly lower rate of seroconversion was observed in patients with hematological malignancies (85%), particularly recipients of anti-CD20 therapies (70%) and stem cell transplantation (74%). Patients receiving immune checkpoint inhibitor therapy (97%) or hormonal therapies (100%) demonstrated high seroconversion post-vaccination. Patients with prior COVID-19 infection demonstrated higher anti-spike IgG titers post-vaccination. Relatively lower IgG titers were noted following vaccination with the adenoviral when compared to the mRNA-based vaccines. These data demonstrate generally high immunogenicity of COVID-19 vaccination in oncology patients and identify vulnerable cohorts that need novel vaccination or passive immunization strategies.