Vaccination against SARS-CoV-2 and risk of hospital admission and death among infected cancer patients: A population-based study in northern Italy

Background: The risks of hospital admission for COVID-19-related conditions and all-cause death of SARS-CoV-2 infected cancer patients were investigated according to vaccination status.Methods: A population-based cohort study was carried out on 9754 infected cancer patients enrolled from January 1, 2021 to June 30, 2022. Subdistribution hazard ratio (SHRs) or hazard ratios (HRs) with 95 % confidence intervals (CI), adjusted for sex, age, comorbidity index, and time since cancer incidence, were computed to assess the risk of COVID-19 hospital admission or death of unvaccinated vs. patients with at least one dose of vaccine (i.e., vaccinated).Results: 2485 unvaccinated patients (25.5 %) were at a 2.57 elevated risk of hospital admission (95 % CI: 2.13-2.87) and at a 3.50 elevated risk of death (95 % CI: 3.19-3.85), as compared to vaccinated patients. Significantly elevated hospitalizations and death risks emerged for both sexes, across all age groups and time elapsed since cancer diagnosis. For unvaccinated patients, SHRs for hospitalization were particularly elevated in those with solid tumors (SHR = 2.69 vs. 1.66 in patients with hematologic tumors) while HRs for the risk of death were homogeneously distributed. As compared to boosted patients, SHRs for hospitalization and HRs for death increased with decreasing number of doses.Conclusions: Study findings stress the importance of SARS-CoV-2 vaccines to reduce hospital admission and death risk in cancer patients.