SRP342042 PRJNA772359 SARS-COV-2 VARIANT B.1.621 INFECTION IN MILD SYMPTOMS PATIENT IMMUNIZED WITH COMPLETE CORONAVAC VACCINE SCHEME: A BRIEF CLINICAL DESCRIPTION Vaccine administration is one of the most efficient ways to control the current COVID-19 pandemic. Several vaccines have been approved for emergency use in different countries, generating a decrease in infections, symptoms, and deaths associated with the disease. However, the appearance of SARS-CoV-2 variants can avoid the immunity generated by vaccines. Thus, in patients with a complete vaccine schedule the infection by SARS-CoV-2 may cause symptomatic but also asymptomatic manifestations of the disease. In this report, we describe for the first time the clinical scenario of a patient of 35 years old infected by the variant of interest (VOI) B.1.621 (Mu), and mild symptomatic development of the disease. the infection takes place after 50 days of completing the vaccination schedule with Coronovac (Sinovac Life Science). This report evidences the importance of maintaining a constant active search for cases in patients with a complete vaccination and evaluate any symptoms in infected patients. the absence of symptoms could underestimate viral circulation and put the unvaccinated population at risk. While the symptoms in vaccinated patients could suggest the appearance of new elusive variants of the immune system and force the application of new public health policies.