The Effect of Vaccination with Pfizer- BioNTech or CoronaVac on Disease Prognosis Among Hospitalized COVID-19 Patients

Objective: The Turkish Ministry of Health offered two types of vaccines by January 13, 2021, which are CoronaVac (Sinovac Biotech, China) and Pfizer-BioNTech. We aimed to describe the impact of the CoronaVac and Pfizer-BioNTech vaccines on clinical outcomes among hospitalized patients during a six-month period. Methods: We included patients older than 18 years old and hospitalized because of COVID-19 when the vaccines were available. We conducted the study at Koc University Hospital and American Hospital between June 2021, six months after the vaccination started, and December 2021. Results: In total, 444 RT-PCR confirmed hospitalized patients were included. The mean age of the patients was 59 (standard deviation [SD]=18), and 42.8% were female. The most common comorbidity was hypertension (39%), followed by diabetes mellitus (27%), cardiovas-cular diseases (18.4%), chronic lung diseases (14.6%), cancer (9.2%), and chronic renal dis-eases (8%). In multivariate analysis, no vaccination (OR=4.7, CI=2.25-10.06; p 0.001), age 65 (OR=5.2, CI=2.25-11.98; p<0.001), cancer (OR=7.6, CI=3.04-19.31; p<0.001), and chronic kidney disease (OR=3.1, CI=1.14-8.74; p=0.026) significantly increased mortality in COVID-19 patients. Eighteen percent of patients were in the intensive care unit (ICU). One hundred eighty-one patients (40.8%) were non-vaccinated before their admission, and their mortality (17.6%) was higher compared to the patients who were vaccinated with at least one type of vaccine (p=0.002). None of the patients who received two doses of Pfizer-BioNTech vaccines died. Conclusion: Among the inpatients with COVID-19, the predictors for mortality were being unvaccinated, older age, cancer, chronic kidney disease, and cardiovascular diseases. Among the vaccinated inpatients, having two doses of the Pfizer-BioNTech vaccine was the only effective protective measure against mortality, and two doses of the CoronaVac vaccine had no significant effect in preventing fatality.