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.

Methods: We performed a retrospective cohort study of cancer patients with COVID-19 diagnosed by polymerase chain reaction on nasal swabs between January 1, 2021 and July 30, 2021. Outcomes of interest included hospitalization, severe COVID-19, and 30-day COVID-19 attributable mortality. Univariate and multivariate analyses were performed to identify factors associated with clinical outcomes, using vaccination status as a variable of interest in all models.

Results: Key risk factors, such as age ≥ 60 years; comorbidities including diabetes mellitus, heart failure, and lung diseases; and specific cancer types (leukemia and lymphoma) were independently associated with hospital admission for COVID-19, severe COVID-19, and 30-day COVID-19 attributable mortality in cancer patients regardless of their vaccination status. Vaccinated patients were protected against severe COVID-19 but with no impact on hospitalization or mortality due to COVID-19.

Conclusion: Our study highlights a significant benefit of COVID-19 vaccination for cancer patients-specifically its protection against severe COVID-19.