A retrospective analysis of the clinical characteristics of vaccinated COVID-19 patients admitted to a tertiary Hospital, Northern Iran

Coronavirus disease 2019 (COVID-19) vaccines have played a critical role in reducing the severity and complications of severe acute respiratory syndrome coronavirus 2 (SARS‑CoV‑2) infection. While various vaccine types have been administered globally, the clinical manifestations of COVID-19 among vaccinated individuals may differ based on the number of doses received. This study aimed to evaluate and compare the initial clinical characteristics of vaccinated COVID-19 patients. This retrospective descriptive-analytical study was conducted on 594 adult patients with confirmed COVID-19 who had received at least one dose of a COVID-19 vaccine. Patients were admitted to Razi Hospital in Rasht, Iran, between June 6, 2021 and March 21, 2022. Medical records were reviewed to collect demographic data, vaccination history, and clinical symptoms at admission. Patients were categorized into three groups: one dose, two doses, and three doses (booster). Clinical symptoms and oxygen saturation levels were compared across these groups. Among 594 patients, 30% had received one dose, 55.1% two doses, and 15% three doses of a COVID-19 vaccine. Fever, cough, myalgia, respiratory distress, and anosmia showed significant differences across the groups. The mean oxygen saturation was highest in the two-dose group. No significant differences were observed in comorbidities among the groups. The number of vaccine doses received was associated with differences in several clinical symptoms and oxygen saturation levels among hospitalized patients. These findings suggest a possible dose-related trend in clinical presentation among vaccinated individuals.