Sinovac vaccination and the course of COVID-19 disease in hospitalized patients in Turkey.

Background: The Alpha variant of SARS-CoV-2 has a higher transmission rate than the first variant identified. The efficacy of vaccines is affected by the characteristics of SARS-CoV-2 variants.

Objective: Investigate the relationship of vaccination and virus variant on the course of the disease in patients who were hospitalized with a diagnosis of COVID-19.

Design: Retrospective, cohort study SETTING: Tertiary health institution PATIENTS AND METHODS: The study included patients older than the age of 18 years who were hospitalized in a COVID-19 service or the intensive care unit with a diagnosis of COVID-19 between 1 January 2021 and 30 April 2021. Demographic characteristics, vaccination and the Alpha virus variant status, comorbidities, and information about hospitalization were obtained from the hospital automation system and patient files.

Main outcome measures: Vaccination rate and relationship with course of disease.

Sample size: 608 RESULTS: Most of the patients (n=482, 79.3%) were admitted to the COVID-19 service. More of the COVID-19 service patients had the Alpha variant than the patients admitted to ICU (P<.009). The Alpha variant was also more common in younger patients (P<.001). There was no relationship between the Alpha virus and comorbid diseases such as diabetes mellitus and hypertension. Mortality was lower in the patients who had received a second dose of the Sinovac vaccine (P=.004) compared with unvaccinated patients.

Conclusion: Although the Alpha variant spreads faster, it has a milder course. If only the Sinovac vaccine is available, we recommend that the two doses of the Sinovac vaccine be administered.

Limitations: Our study is single-center and did not include pregnant and pediatric patients.

Conflict of interest: None.