Vaccine Efficacy in Preventing COVID-19 and Modifying Disease Outcomes: A Comparative Evaluation of BNT162b2 and CoronaVac

INTRODUCTION: Aims: This study aims to evaluate the comparative efficacy of the BNT162b2 and Sinovac vaccines in controlling the COVID-19 pandemic through the implementation of large-scale vaccination programs.
METHODS: This retrospective study was conducted in the tertiary emergency department of a university hospital. Patients hospitalized for COVID-19 were categorized into vaccinated and unvaccinated groups to compare clinical outcomes. Data collected included demographics (age, gender), hospitalization status, vaccination schedule, and mortality. The effectiveness of the BNT162b2 and CoronaVac vaccines was subsequently evaluated
RESULTS: Of 633 patients, 297 (47%) were male and 336 (53%) female, with a mean age of 61.2 ± 16.8 years. At COVID-19 diagnosis, 171 (27%) were vaccinated, and 462 (73%) were unvaccinated. Among 305 unvaccinated patients, 104 (16.4% of the total) died during hospitalization. In striking contrast, only four deaths occurred among 269 patients receiving two or more vaccine doses (BNT162b2: 0; CoronaVac: 4). Hospital admissions included 488 (71.1%) to general wards and 145 (22.9%) to the ICU.
Comorbidities were present in 393 patients (62.1%): hypertension (33.8%), diabetes mellitus (22.4%), COPD (14.2%), heart failure (13.7%), and cancer (11.4%). PCR was positive in 437 (69.0%). Pulmonary involvement consistent with COVID-19 was detected in 271 (42.8%).
DISCUSSION AND CONCLUSION: Current evidence unequivocally demonstrates that administration of at least two doses of the COVID-19 vaccine provides significant protection and markedly reduces mortality rates. Nevertheless, even among vaccinated individuals, underlying chronic comorbidities remain a strong and independent risk factor for mortality during the course of COVID-19.

Keywords: COVID-19, BNT162b2, CoronaVac, vaccine effectiveness, mortality