COVID-19 in cancer patients: The impact of vaccination on outcomes early in the pandemic.

Background: With the rapid evolution of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic, the development of effective and safe vaccines was of utmost importance to protect vulnerable individuals, including cancer patients. Studies comparing the clinical outcomes of cancer patients with or without vaccination against coronavirus disease 2019 (COVID-19) have not demonstrated clear benefit. We aimed to determine the protective effects of COVID-19 vaccination by comparing vaccinated and unvaccinated cancer patients after the initial phase of vaccine roll-out and to identify risk factors associated with hospitalization, severe COVID-19, and 30-day COVID-19 attributable mortality.