COVID-19, SARS-CoV-2, Vaccine, Third wave, Saudi Arabia, Omicron, Infectious and parasitic diseases, RC109-216, Public aspects of medicine, RA1-1270

Introduction: The third (Omicron) wave had caused significant increase in the number of COVID-19 cases around the globe. The severity of the disease dependeds on the extent of the vaccination status. Methods: This is a retrospective study of infected COVID-19 patients during the third (Omicron) wave in a hospital in Saudi Arabia. Results: A total of 400 patients were included with 220 (55 %) males and 180 (45 %) females, and a mean age (+/- SD) of 36.34 + 16.47 years. The most common presenting symptoms were: sore throat 159 (39.8 %), cough 158 (39.5 %), fever 132 (33 %), headache 122 (30.5 %), and muscle ache 124 (31%). There was no difference in underlying conditions, signs and symptoms between males and females apart from the occurrence of sore throat with an OR of 2.014 (95 % CI: 1.103–3.677, P = 0.023) and need of hospitalization OR 2.457 (95 % CI: 1.168–5.167, P value =.018) in a binary logistic regression comparison. The need for hospitalization was inversely related to the number of COVID-19 vaccination doses. The rate of admission was 8 (72.7 %), 34 (12 %), 4 (5.4 %) for one, two, and three doses of COVID-19 vaccine, respectively (P