key: cord-0750842-qtfbgyi0 authors: Busic, Nikolina; Lucijanic, Tomo; Barsic, Bruno; Luksic, Ivica; Busic, Iva; Kurdija, Goran; Barbic, Ljubo; Kunstek, Sanja; Jelic, Tea; Lucijanic, Marko title: Vaccination provides protection from respiratory deterioration and death among hospitalized COVID‐19 patients: Differences between vector and mRNA vaccines date: 2022-02-26 journal: J Med Virol DOI: 10.1002/jmv.27666 sha: cb4b21eae43148fe4bf7a376caea6e8a06f9e1ae doc_id: 750842 cord_uid: qtfbgyi0 Outcomes of 109 hospitalized COVID‐19 patients who received at least one vaccine dose 14 or more days prior the disease onset were retrospectively compared to control cohort of 109 age, sex, and Charlson comorbidity index‐matched patients chosen among 2990 total hospitalized patients in our tertiary‐level institution in a period from January to June 2021. Among 109 vaccinated patients, 84 patients were partially and 25 fully vaccinated. Vaccinated patients experienced significantly lower 30 days mortality (30% vs. 49%; hazard ratio [HR]: 0.56 [0.37–0.85]; p = 0.008), less frequently required high flow oxygen therapy (17% vs. 34%; HR: 0.45 [0.26–0.76]; p = 0.005), and mechanical ventilation (8% vs. 18%; HR: 0.41 [0.20–0.88]; p = 0.027) in comparison to the matched cohort of unvaccinated patients. More favorable survival was observed in patients receiving vector in comparison to messenger RNA (mRNA) vaccine types in unadjusted analysis (30 days mortality 18% vs. 40%; HR: 0.45 [0.25–0.79]; p = 0.034). In the multivariable Cox regression analysis model both mRNA (HR: 0.59 [0.36–0.98]; p = 0.041) and vector vaccine types (HR: 0.30 [0.15–0.60]; p < 0.001) were associated with improved survival in comparison to unvaccinated patients, independently of age (HR: 1.03 [1.01–1.06]; p = 0.011), male sex (HR: 1.78 [1.14–2.76]; p = 0.010), severity of illness (HR: 2.06 [1.36–3.10]; p < 0.001) and functional status on admission (HR: 1.42 [1.07–1.85]; p = 0.013). January 27th, 2020 and the first available were mRNA vaccines for priority groups of population (older, long-term facility residents, healthcare workers, care home workers, immunocompromised patients). From mid-February 2021 there are also vector vaccines on disposition and mass vaccination of the general population started from April 2021 with all four available vaccines. All of them have proven their safety and efficacy, 3-6 not only in fully vaccinated then also in incomplete vaccinated population for BNT162b2 and ChA-dOx1 nCoV-19 vaccines. Notably, a great effect of a single dose against hospital admissions and mortality has been reported. 7 Due to the inability of vaccines to completely prevent the development of COVID-19, patients exposed to COVID-19 vaccines can still be hospitalized and encountered in clinical wards. Their clinical course is unknown. Thus, we aimed to investigate the clinical characteristics and disease course of these patients by analyzing a large cohort of real-life hospitalized COVID-19 patients from a tertiary institution. We have retrospectively analyzed hospitalized COVID-19 patients treated in our tertiary-level institution (University hospital Dubrava) in the period from January 2021 to June 2021. Among 2990 patients, we have identified a total of 109 patients who received at least one dose of anti-SARS-CoV-2 vaccine ≥14 days before hospitalization and compared them to 1:1 age, sex, and Charlson comorbidity index (CCI) matched cohort of hospitalized but unvaccinated patients. Matching procedure was done without COVID-19 severity on admission as a criterion with the aim of assessing the potential difference in severity between vaccinated and unvaccinated patients, however proportion of severe or critical disease was well balanced between the two groups (there was no significant difference in the proportion of patients with severe or critical disease on presentation). CCI was chosen for quantification of comorbidity burden as a validated measure with prognostic implications in COVID-19 patients due to the fact that the matching procedure could not be performed using a large number of comorbidities. Specific comorbidities were well balanced between the two groups after matching (no significant difference). The subgroup of patients exposed to single-dose with illness onset <14 days after vaccination (75 patients) was excluded from analyses. Data on baseline characteristics and clinical course of patients are a part of the hospital registry project and were obtained through analysis of written and electronic medical records. Data on vaccination were collected from vaccination certificates or by plausible self-report if they provided the number of vaccination doses, dates, and type of vaccine and were checked at the national immunization registry. All patients were tested COVID-19 positive by polymerase chain reaction or antigen test. COVID-19 severity was graded based on the World Health Organization recommendations as mild, moderate, severe, and critical. The study was approved by the Institutional Review Board. The normality of the distribution of numerical variables was analyzed using the Shapiro-Wilk test. Numerical variables were presented as the median and interquartile range (IQR) and were compared between groups using the Kruskal-Wallis one-way analysis of variance. Categorical variables were presented as frequencies and percentages and were compared between groups using the χ 2 test. Survival analyses were based on the Kaplan-Meier method. The Adjustments for some of the factors also used for matching of the control group were deliberately implemented to control the analysis for potential small differences between vaccinated and unvaccinated patients as well as for heterogeneity of vaccinated group of patients due to the retrospective data set and obligation to ameliorate as much bias as possible. p < 0.05 were considered to be statistically significant. All analyses were performed using the MedCalc statistical software ver 20.010 (MedCalc Software Ltd.). The median age of COVID-19 patients hospitalized after vaccination was 82 years, IQR (73-86). There were 59/109 (54.1%) males. Median CCI was 5 points, IQR (4-7). Severe or critical COVID-19 on admission was present in 100/109 (91.7%) patients. Patients' characteristics are shown in Table 1 . We further compared clinical outcomes of the cohort of vaccinated patients with the age, sex, and CCI-matched control cohort of 109 patients. Baseline patient characteristics were well balanced between two groups as shown in Table 1 with the majority of severe and critical patients and for the specific context of low vaccination rates in the general population at the start of the vaccination program (ranging from <5% to 30% over the study period). They also represent the pandemic period of second and third disease waves that were dominated by alpha and beta The authors declare no conflict of interest. The study was approved by the University Hospital Dubrava Review Board. All authors fulfilled ICMJE authorship criteria and agree to be ac- Data available on reasonable request. 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