BMC Infectious Diseases (Sep 2024)

Comprehensive statistical analysis reveals significant benefits of COVID-19 vaccination in hospitalized patients: propensity score, covariate adjustment, and feature importance by permutation

  • Eduardo Villela de Moraes,
  • Magda Carvalho Pires,
  • Amanda Abrantes Abreu Costa,
  • Aline Gabrielle Sousa Nunes,
  • Caroline Lopes de Amorim,
  • Euler Roberto Fernandes Manenti,
  • Fernanda Barbosa Lucas,
  • Fernanda d’Athayde Rodrigues,
  • Fernando Anschau,
  • Guilherme Fonseca do Nascimento,
  • Giovanna Grunewald Vietta,
  • Jessica Fernandes Benavides Moreira,
  • Karen Brasil Ruschel,
  • Monica Aparecida Costa,
  • Pamela Andrea Alves Duraes,
  • Pedro Augusto Van Der Sand Germani,
  • Priscilla Pereira dos Reis,
  • Rochele Mosmann Menezes,
  • Leonardo Chaves Dutra da Rocha,
  • Marcos André Gonçalves,
  • Unaí Tupinambas,
  • Milena Soriano Marcolino

DOI
https://doi.org/10.1186/s12879-024-09865-1
Journal volume & issue
Vol. 24, no. 1
pp. 1 – 12

Abstract

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Abstract Background 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. Methods 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. Results 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. Conclusion 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.

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