Vaccines against acute respiratory syndrome Coronavirus 2(SARS-CoV2) are critical weapons to control the spread of the deadly Coronavirus 2019(COVId-19) virus worldwide. Although these vaccines are generally safe, their widespread use has produced reports of rare complications, including vaccine-induced immune thrombotic thrombocytopenia (VIITT), particularly in connection with ChAdOx1 nCov-19. We have identified three cases of sickle cell disease (SCD) experiencing a severe vaso-occlusive crisis (VOC) shortly after the vaccine. Despite being stable for a long time, they had fever with tachycardia, along with a significant rise in WBC, liver enzymes, particularly alkaline phosphate, with a remarkable drop in hemoglobin, and platelets and one of them had probably a fatal TTP like syndrome. Given these findings, physicians and patients should exercise caution when taking this type of vaccine and be aware of these safety concerns.