Medical School and University Hospital, Universidade Federal de Minas Gerais, Av. Professor Alfredo Balena, 110, Belo Horizonte, CEP 30130-100, Brazil.
Department of Statistics, Universidade Federal de Minas Gerais, Av. Presidente Antônio Carlos, 6627, ICEx, sala 4071, Belo Horizonte, Brazil.
BMC Infect Dis. 2024 Sep 27;24(1):1052. doi: 10.1186/s12879-024-09865-1.
COVID-19 vaccines effectively prevent infection and hospitalization. However, few population-based studies have compared the clinical characteristics and outcomes of patients hospitalized for COVID-19 using advanced statistical methods. Our objective is to address this evidence gap by comparing vaccinated and unvaccinated patients hospitalized for COVID-19.
This retrospective cohort included adult COVID-19 patients admitted from March 2021 to August 2022 from 27 hospitals. Clinical characteristics, vaccination status, and outcomes were extracted from medical records. Vaccinated and unvaccinated patients were compared using propensity score analyses, calculated based on variables associated with vaccination status and/or outcomes, including waves. The vaccination effect was also assessed by covariate adjustment and feature importance by permutation.
From the 3,188 patients, 1,963 (61.6%) were unvaccinated and 1,225 (38.4%) were fully vaccinated. Among these, 558 vaccinated individuals were matched with 558 unvaccinated ones. Vaccinated patients had lower rates of mortality (19.4% vs. 33.3%), invasive mechanical ventilation (IMV-18.3% vs. 34.6%), noninvasive mechanical ventilation (NIMV-10.6% vs. 22.0%), intensive care unit admission (ICU-32.0% vs. 44.1%) vasoactive drug use (21.1% vs. 32.6%), dialysis (8.2% vs. 14.7%) hospital length of stay (7.0 vs. 9.0 days), and thromboembolic events (3.9% vs.7.7%), p < 0.05 for all. Risk-adjusted multivariate analysis demonstrated a significant inverse association between vaccination and in-hospital mortality (adjusted odds ratio [aOR] = 0.42, 95% confidence interval [CI]: 0.31-0.56; p < 0.001) as well as IMV (aOR = 0.40, 95% CI: 0.30-0.53; p < 0.001). These results were consistent in all analyses, including feature importance by permutation.
Vaccinated patients admitted to hospital with COVID-19 had significantly lower mortality and other severe outcomes than unvaccinated ones during the Delta and Omicron waves. These findings have important implications for public health strategies and support the critical importance of vaccination efforts, particularly in low-income countries, where vaccination coverage remains suboptimal.
COVID-19 疫苗能有效预防感染和住院。然而，很少有基于人群的研究使用先进的统计方法比较 COVID-19 住院患者的临床特征和结局。我们的目的是通过比较 COVID-19 住院患者的疫苗接种和未接种情况来填补这一证据空白。
这项回顾性队列研究纳入了 2021 年 3 月至 2022 年 8 月期间，来自 27 家医院的因 COVID-19 住院的成年患者。从病历中提取临床特征、疫苗接种情况和结局。采用倾向评分分析比较接种组和未接种组，基于与疫苗接种状态和/或结局相关的变量进行计算，包括波次。通过协变量调整和置换特征重要性评估疫苗接种效果。
在 3188 名患者中，1963 名（61.6%）未接种，1225 名（38.4%）完全接种。其中，558 名接种者与 558 名未接种者进行了匹配。接种组的死亡率（19.4% vs. 33.3%）、有创机械通气（IMV-18.3% vs. 34.6%）、无创机械通气（NIMV-10.6% vs. 22.0%）、入住重症监护病房（ICU-32.0% vs. 44.1%）、血管活性药物使用（21.1% vs. 32.6%）、透析（8.2% vs. 14.7%）、住院时间（7.0 天 vs. 9.0 天）和血栓栓塞事件（3.9% vs. 7.7%）均较低，p 值均<0.05。风险调整的多变量分析显示，疫苗接种与住院死亡率（调整后比值比[aOR] = 0.42，95%置信区间[CI]：0.31-0.56；p<0.001）和有创机械通气（aOR = 0.40，95% CI：0.30-0.53；p<0.001）之间存在显著的负相关。这些结果在所有分析中均一致，包括置换特征重要性分析。
在 Delta 和 Omicron 波次期间，接种 COVID-19 疫苗的住院患者的死亡率和其他严重结局显著低于未接种患者。这些发现对公共卫生策略具有重要意义，并支持疫苗接种工作的重要性，特别是在疫苗接种覆盖率仍然不理想的低收入国家。
