ABSTRACT
Patients with cancer are at significantly greater risk of COVID-19 and its complications than the general population. Since IgG antibodies remain detectable well after infection with the SARS-CoV-2 virus, seroprevalence can be used to estimate the proportion of the cancer population previously infected and potentially immune to SARS-CoV-2. The current study is a multi-center, prospective observational study to assess the seroprevalence of SARS-CoV-2 IgG antibody in a cancer population referred for vaccination between April and June 2021. Of a total of 270 adult patients with cancer accrued, 16% reported a history of COVID-19 more than four weeks previously confirmed by PCR. At the same time, serologic positivity for SARSCoV2 IgG was found in 29% of patients prior to vaccination including nearly 20% of patients without a history of confirmed COVID-19. Seropositivity was significantly greater in females consistent with higher rates in patients with breast cancer and gynecologic cancers. A seroconversion rate of 79.5% was observed in cancer patients with a history of PCR confirmed COVID-19, less than observed in the general population. In multivariable analysis, gender and prior history of COVID-19 were both independently associated with seropositivity prior to vaccination. Follow-up is continuing of this cohort of patients with cancer following vaccination to assess antibody and clinical outcomes.