Post-vaccination side effects of AstraZeneca (AZ) coronavirus disease 2019 (COVID-19) vaccine are common. Severe acute respiratory syndrome coronavirus 2 (SARS-CoV2) infection immediately after the first dose of AZ COVID-19 vaccine has not been reported. In this case, a 30-year-old female without a past medical history of SARS-CoV2 infection presented to an outpatient clinic with lightheadedness and weakness 2 hours after getting the first dose of the AZ COVID-19 vaccine. Blood pressure (BP) was 80/60 mm Hg, and oxygen saturation (SpO2) was 98%. After administering normal saline intravenous fluid, the BP was 110/80 mm Hg. On the first day, fever (oral temperature of 39℃), sweating, dry cough, sore throat, and injection-site pain were presented. On the second day, diarrhea, productive cough, and hypotension occurred in addition to fever (oral temperature of 39.9℃). The fever did not stop and productive cough, change in smell, and fatigue were reported. SpO2 was 96%. On the third day, no abnormality of the spiral lung computed tomography and the positive reverse transcriptase-polymerase chain reaction (RT-PCR) test were reported. Simultaneously, two out of three members of the family became symptomatic on the second day and their RT-PCR tests were positive. Dexamethasone ampule, Cefixime tablet, Acetaminophen tablet, and Diphenhydramine syrup were prescribed. After a week, fever subsided and SpO2 was 98%. After 3 weeks of self-quarantine at home, her general condition improved. Despite the similarity between SARS-CoV2 infection signs and symptoms and AZ COVID-19 vaccine side effects, none of the approved vaccines contain the live virus that causes disease. Therefore, any unusual post-vaccination signs and symptoms should not be attributed to the vaccine itself and need to be considered for further evaluations and early actions in order to prevent the spread of the disease in society.