COVID-19 vaccination and lethality reduction: a prospective observational study in Venezuela during the last two waves

Abstract Background In Venezuela, the predominant vaccines administered are BBIBP-CorV and Gam-COVID-Vac. Despite robust evidence from randomized clinical trials validating the effectiveness of COVID-19 vaccines in mitigating hospitalization and mortality, there is still a lack of post-authorization safety studies conducted within this demographic population. Methods A prospective observational study from October 5, 2021 to March 31, 2022 encompassed COVID-19 vaccinated and unvaccinated patients from four sentinel hospitals in Venezuela. Patient lethality was predicted using Charlson Comorbidity index. Clinical outcomes were assessed through WHO’s COVID-19 Clinical Progression Scale. Results Out of the 175 patients assessed, 85 (48.6%) were vaccinated. The median Charlson Comorbidity index was 3 points, with no statistically significant differences observed between the groups ( p = 0.2). A total of 50 (28.6%) patients died during the study period, with higher proportion of deaths in unvaccinated patients (35.6% vs. 21.2%, p = 0.035). Advanced age (OR = 1.043, 95% CI = 1.015–1.071, p = 0.002) was associated with increased death risk, whereas vaccination against COVID-19 (OR = 0.428, 95% CI = 0.185–0.99, p = 0.047), high oxygen saturation (OR = 0.964, 95% CI = 0.934–0.995, p = 0.024), and enoxaparin administration (OR = 0.292, 95% CI = 0.093–0.917, p = 0.035) were associated with decreased death risk. Conclusion During the third and fourth waves of the pandemic, COVID-19 vaccination was associated with a 57% reduction in lethality among patients in four public hospitals in Venezuela.