A majority of patients having active systemic treatment for cancer developed an adequate immune response to the Pfizer/BioNTech COVID-19 vaccine, suggested a prospective cohort study.

Overall, 90% of the patients with solid tumors taking active intravenous cancer treatment were found to be seropositive for SARS-CoV-2 antispike IgG antibodies following the second dose of the vaccine (BNT62b2). However, the antibody titers in these patients were significantly lower compared to those of healthy controls, reported researchers. 

Ninety two out of a total of 102 cancer patients enrolled in the study were seropositive for SARS-CoV-2 antispike IgG antibodies following the second vaccine dose, compared to 100% of the controls... (Medpage Today)