Many people fear from COVID.19 vaccines, due to rapid production of it, that made them doubt about the value of its clinical trials. Individuals with chronic diseases, particularly renal patients, whom are not able to excrete exogenous estradiol in level, and high level of estradiol may activate coagulation system presence of high level of proinflammatory cytokines interlukein-6, which cause tissue injury, activation of thrombin and aggregation of platelets, and presence of factor XI in some types of COVID.19 Vaccine may lead to great risk of thrombosis, that may lead to deadly complications, certainly among women.