The challenges in controlling the pandemic have been exacerbated by the disease's morbidity and the emergence of additional COVID-19 variants. The use of emergency vaccines to circumvent these challenges has sparked mixed opinions on their effectiveness. Therefore, we conducted a meta-analysis to assess the efficacy of COVID-19 vaccines on clinical outcomes such as incidence, hospitalization, and ventilation rates in both vaccinated and unvaccinated patients. PubMed, Google Scholar, and Cochrane Central Register of Clinical Trials were searched on April 21, 2022, to extract published articles comparing vaccinated COVID-19 patients versus unvaccinated COVID-19 patients and their clinical outcomes. The clinical outcomes studied were incidence rate, intensive care unit (ICU) admission, mechanical ventilation, and hospitalization rates. The analysis was performed with Review Manager (RevMan) software. Random-effect models were used to calculate pooled odds ratio and corresponding 95% confidence interval (CI). In our meta-analysis, we have identified a total of 250 published findings, encompassing 15 studies that involved a cumulative count of 24,164,227 individuals diagnosed with COVID-19. Being unvaccinated had a significant association with severe clinical outcomes in patients infected with COVID-19. Unvaccinated individuals were 2.36 times more likely to be infected, with a 95% CI ranging from 1.13 to 4.94 (p = 0.02). Unvaccinated subjects with COVID-19 infection were 6.93 times more likely to be admitted to the ICU than their vaccinated counterparts, with a 95% CI ranging from 3.57 to 13.46 (p < 0.0001). The hospitalization rate was 3.37 higher among the unvaccinated compared to those vaccinated, with a 95% CI ranging from 1.92 to 5.93 (p < 0.0001). In addition, patients with COVID-19 infection who are unvaccinated were 6.44 times more likely to be mechanically ventilated than those vaccinated, with a 95% CI ranging from 3.13 to 13.23 (p < 0.0001). Overall, our study revealed that vaccination against COVID-19 disease is beneficial and effective in mitigating the spread of the infection and associated clinical outcomes. However, more awareness and proper education must be made to increase vaccine acceptance. We, therefore, recommend and urge all stakeholders involved in COVID-19 prevention, management, and control to strengthen awareness and educate the people on the effectiveness of COVID-19 vaccination.

Keywords: coronavirus disease (covid-19); covid-19 vaccine; covid-19 vaccine progress; icu admissions; incidence rate; mechanical ventilation; rate of hospitalization; vaccination status.

Copyright © 2023, Ikeokwu et al.