Objective COVID-19 vaccines have shown efficacy and safety in healthy people. However, cancer patients under active immunosuppressive treatment were not included in the clinical trials conducted to test vaccines' efficacy and safety. This study aimed to evaluate the COVID-19 vaccine acceptance in cancer patients undergoing immunosuppressive therapy. Methods A total of 200 adult cancer patients received a questionnaire between March 8 and April 2, 2021, before the beginning of cancer patients' vaccination in Portugal. The questionnaire adapted from previously conducted studies included 11 close-ended items, evaluating variables such as patient sociodemographic and clinical characteristics, and the acceptance and underlying reasons to be or not to be vaccinated. The primary outcome was the intended acceptance of the COVID-19 vaccine in cancer patients. Multiple logistic regression was performed to identify factors associated with intended acceptance. Results Among the 200 delivered questionnaires, only 169 were included in this study. From those, 142 (84%) patients intended to be vaccinated against COVID-19. Only 27 participants (16%) had not yet decided or were reluctant to COVID-19 vaccination. High school degree (odds ratio (OR) 0.133, 95% confidence interval (C.I.) 0.031-0.579, p = 0.007], rural residence (OR 0.282, 95% C.I. 0.081-0.984, p = 0.047), and reluctance in believing in the vaccine efficacy (OR 0.058, 95% C.I. 0.016-0.204, p < 0.001] were identified predictors factor for COVID-19 vaccine hesitancy. Conclusion Most patients intended to be vaccinated against COVID-19, and specific factors such as education level, rural residence and the belief in vaccine efficacy were related to vaccine acceptance.

Background: Cancer p represent a high-risk population for severe COVID-19. Cancerassociated immunosuppression may hinder in the development of anti-SARS-CoV-2 antibodies.