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Clinical outcomes in vaccinated and unvaccinated patients with COVID-19: a population-based analysis
O Papaioannou1, T Karampitsakos, P Tsiri
1Department of Respiratory Medicine, Department of Internal Medicine, Department of Hematology, University Hospital of Patras, Patras, Greece. atzouvelekis@upatras.gr.
Insights
COVID-19 vaccination significantly reduces hospitalization and mortality risks. Booster doses are crucial, especially during the Omicron variant era, to maintain protection against severe outcomes.
Area of Science:
- Epidemiology
- Infectious Diseases
- Public Health
Background:
- Real-world data on COVID-19 vaccine effectiveness is essential for public health policy.
- Population-based analyses are critical for understanding vaccine impact on hospitalization and mortality.
Purpose of the Study:
- To investigate the hospitalization risk for COVID-19 in a large population.
- To compare the characteristics and outcomes of vaccinated versus unvaccinated patients.
Main Methods:
- A population-based analysis of 98,982 subjects was conducted.
- Included hospitalized COVID-19 patients between July 1, 2021, and February 11, 2022.
- Compared hospitalization risk, duration, and mortality between vaccinated and unvaccinated groups.
Main Results:
- Unvaccinated individuals faced a significantly higher risk of hospitalization (HR: 2.82) and mortality (HR: 2.59) compared to vaccinated individuals.
- Vaccinated patients were older, with a median latency of 5.7 months from the second dose to hospitalization.
- Hospitalization duration was longer in unvaccinated patients.
Conclusions:
- COVID-19 vaccination is the most effective strategy for pandemic control.
- Booster doses are necessary to maintain protection, particularly during the Omicron variant surge.
Objective:
Real-life data for vaccination against COVID-19 are sorely needed. This was a population-based analysis aiming at investigating the hospitalization risk for COVID-19 of 98,982 subjects and compare features of vaccinated and unvaccinated patients.
Patients And Methods:
Hospitalized patients with COVID-19 between 01/07/2021 and 11/02/2022 were included in the study.
Results:
582 patients were included in the analysis [males: 58.6% (n=341), vaccinated patients: 28.5% (n=166), unvaccinated patients: 71.5% (n=416)]. Median age of vaccinated patients was significantly higher compared to median age of unvaccinated [74.0 (95% CI: 72.0-77.0) vs. 59.0 (95% CI: 57.0-62.0), p=0.0001]. Mean latency time (±SD) from the second dose to hospitalization was 5.7±2.6 months. Between 01/07/2021 and 01/12/2021, unvaccinated subjects had higher risk for hospitalization compared to vaccinated [HR: 2.82, 95% CI: 2.30-3.45, p<0.0001]. Between 02/12/2021 and 11/02/2022, unvaccinated subjects presented with higher risk for hospitalization than subjects that had received booster dose [HR: 2.07, 95% CI: 1.44-2.98, p=0.005], but not than subjects that got two doses. Median value of hospitalization days was higher in unvaccinated patients compared to vaccinated [7.0 (95% CI: 7.0-8.0) vs. 6.0 (95% CI: 5.0-7.0), p=0.02]. Finally, age-adjusted analysis showed that hospitalized unvaccinated patients presented with significantly higher mortality risk compared to hospitalized vaccinated patients [HR: 2.59, 95% CI: 1.69-3.98, p<0.0001].
Conclusions:
Vaccination against COVID-19 remains the best way to contain the pandemic. There is an amenable need for booster dose during the omicron era.
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