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BMC Infect Dis
. 2025 Oct 31;25(1):1457.
doi: 10.1186/s12879-025-11904-4. Comparison of fully-vaccinated and non/partially-vaccinated critically-ill COVID-19 patients in terms of disease severity: a retrospective observational study
Guillaume Louis 1 2 , Vincent Dinot 3 , Thibaut Belveyre 4 , Ophélie Dirand 5 , Paul Dunand 6 , Cyril Cadoz 5 , Rostane Gaci 5 , Sébastien Gette 5 6 , Pascale Perez 7 , Christophe Goetz 3 , Yoann Picard 5 , Nouchan Mellati 5
Affiliations
Background: Critical care admissions due to breakthrough COVID-19 in fully vaccinated patients remain rare. There is limited data on their characteristics and outcomes compared to non- or partially vaccinated patients, and no studies have evaluated the impact of variants of concern.
Method: This study used the COMETE-19 (COVID-19 patients in the intensive care unit [ICU]) near real-time prospective registry, a tool launched on March 1, 2020, to track patient and disease characteristics as well as the disease course of critically ill COVID-19 patients in two French ICUs. Fully vaccinated patients were compared with non- or partially vaccinated patients. The primary outcome was a composite criterion of severity, including invasive mechanical ventilation (IMV), other organ assistance, or death. Differences between the vaccinated and control groups regarding other outcomes, patient variables, management, and SARS-CoV-2 variants were explored using univariate analysis. Factors associated with high disease severity in both groups were examined using logistic regression analysis.
Results: A total of 805 patients (median age, 65 years [IQR 56-71], 67% male) were enrolled. Of these, 41 (5%) were fully vaccinated. Fully vaccinated patients required less frequent IMV (27% vs. 51%, p = 0.003) and had lower mortality (15% vs. 26%, p = 0.026). Full vaccination status was associated with lower disease severity (OR 0.30; CI95% [0.11-0.74]; p = 0.011) and tended to prevent ICU mortality (OR 0.39, CI95% [0.13-1.04], p = 0.072). Variants-of-concern did not associate with outcomes.
Conclusion: Among critically ill COVID-19 patients, full vaccination was associated with less severe disease progression compared to partial or no vaccination.
Trial registration: Clinical Trial: NCT04430322.
Keywords: Breakthrough infection; COVID-19; Intensive care unit; Vaccination; Variants-of-concern.
. 2025 Oct 31;25(1):1457.
doi: 10.1186/s12879-025-11904-4. Comparison of fully-vaccinated and non/partially-vaccinated critically-ill COVID-19 patients in terms of disease severity: a retrospective observational study
Guillaume Louis 1 2 , Vincent Dinot 3 , Thibaut Belveyre 4 , Ophélie Dirand 5 , Paul Dunand 6 , Cyril Cadoz 5 , Rostane Gaci 5 , Sébastien Gette 5 6 , Pascale Perez 7 , Christophe Goetz 3 , Yoann Picard 5 , Nouchan Mellati 5
Affiliations
- PMID: 41174545
- PMCID: PMC12577408
- DOI: 10.1186/s12879-025-11904-4
Background: Critical care admissions due to breakthrough COVID-19 in fully vaccinated patients remain rare. There is limited data on their characteristics and outcomes compared to non- or partially vaccinated patients, and no studies have evaluated the impact of variants of concern.
Method: This study used the COMETE-19 (COVID-19 patients in the intensive care unit [ICU]) near real-time prospective registry, a tool launched on March 1, 2020, to track patient and disease characteristics as well as the disease course of critically ill COVID-19 patients in two French ICUs. Fully vaccinated patients were compared with non- or partially vaccinated patients. The primary outcome was a composite criterion of severity, including invasive mechanical ventilation (IMV), other organ assistance, or death. Differences between the vaccinated and control groups regarding other outcomes, patient variables, management, and SARS-CoV-2 variants were explored using univariate analysis. Factors associated with high disease severity in both groups were examined using logistic regression analysis.
Results: A total of 805 patients (median age, 65 years [IQR 56-71], 67% male) were enrolled. Of these, 41 (5%) were fully vaccinated. Fully vaccinated patients required less frequent IMV (27% vs. 51%, p = 0.003) and had lower mortality (15% vs. 26%, p = 0.026). Full vaccination status was associated with lower disease severity (OR 0.30; CI95% [0.11-0.74]; p = 0.011) and tended to prevent ICU mortality (OR 0.39, CI95% [0.13-1.04], p = 0.072). Variants-of-concern did not associate with outcomes.
Conclusion: Among critically ill COVID-19 patients, full vaccination was associated with less severe disease progression compared to partial or no vaccination.
Trial registration: Clinical Trial: NCT04430322.
Keywords: Breakthrough infection; COVID-19; Intensive care unit; Vaccination; Variants-of-concern.