Many countries have started their vaccination program against the ongoing COVID-19 pandemic. One of these countries, the Republic of Turkey began to use the CoronaVac® vaccine and a large number of people in the country have been vaccinated so far. The efficacy rate of CoronaVac® vaccine 14 days after two doses was reported as 83% for cases requiring medical treatment and 100% for hospitalization or severe- mortal cases. In addition, in a recent study, it was reported that Coronavac vaccine prevented 86.5% death due to covid-19 in the population over 60 years old, 14 days after receiving two doses of CoronaVac. The effectiveness of the vaccine in subgroups such as patients exposed to SARS- CoV-2 virus in less than 14 days, advanced age, comorbidity, and immunosuppression is not yet known. In addition, its effectiveness against different variants of the SARS-CoV-2 virus is not clear. An 85-year-old female patient with a positive SARS-CoV-2 Variant VOC-202012/01 Polymerase Chain Reaction test was admitted to the emergency department with dyspnea. The patient, whose tachycardia, tachypnea and auxiliary respiratory muscle use continued despite 60 L / min of 100% oxygen therapy with a high flow nasal cannula and whose PaO2 / fiO2 ratio was 63, was intubated. Bilateral widespread multifocal ground glass densities consistent with COVID-19 were observed in the thorax computed tomography. The patient, who was followed up in the intensive care unit, died on the 11th day of her follow-up. There are no cases of severe COVID-19 disease reported in the literature yet after the CoronaVac® vaccine. In this case report, we present a severe COVID-19 patient with a positive PCR test for SARS-CoV-2 Variant VOC-202012/01 11 days after the second dose of CoronaVac® administration.