Purpose: The aim of the present study was to investigate characteristics and outcomes in vaccinated and unvaccinated older patients hospitalized for COVID-19 infection.

Methods: A retrospective multicentre cohort study among patients aged ≥70 years hospitalized for COVID-19 infection.

Results: 263 vaccinated and 82 unvaccinated patients were included. Vaccinated patients were older (median age 79 vs. 76 years; p < 0.001), more patients were male (66.2% vs. 53.7%; p = 0.040), had more comorbidities [median Charlson Comorbidity Index (CCI) 2 vs. 1; p 0.016] and were frailer [Clinical Frailty Scale (CFS) ≥ 4 68% vs. 49%; p 0.015]. Vaccinated patients were admitted earlier after symptom onset (median 5 days vs. 7 days) but were equally ill at time of hospital admission. After correction for frailty, comorbidity and disease severity, risk of in-hospital mortality was three times lower for vaccinated patients (HR 0.30 95% CI 0.16-0.56; p < 0.001) compared to unvaccinated patients.

Conclusion: Vaccinated patients had lower risk of in-hospital mortality than unvaccinated patients with COVID-19 infection. These findings suggest that vaccinated patients benefit from the protective effect of the vaccine against death during hospital stay, outweighing the increased mortality risk that is associated with older age, greater frailty and more numerous comorbidities. This could be an encouragement for older people to receive age-appropriate vaccines, although no definite conclusions can be drawn for this was no intervention study.