Purpura after the new coronavirus vaccination may be caused by drug allergy, bacterial infection, pressure at the injection site, etc. It usually does not go away by itself. 1. Drug allergy: After taking the new coronavirus vaccine, the vaccine enters the body, and a metamorphic reaction may occur, which increases the permeability and fragility of the capillary wall, thus triggering purpura. 2. Bacterial infection: If the injection site is not sterilized thoroughly when the new coronavirus vaccine is administered, it may lead to bacterial invasion, causing acute infection and triggering purpura, and a well-defined patchy rash may appear at the border of the skin. 3. Pressure at the injection site: If you wear tight clothes after taking the new coronavirus vaccine, it may lead to increased intravascular pressure and microvascular rupture at the injection site, which may cause subcutaneous hemorrhage and lead to purpura. Purpura after the new coronavirus vaccine usually can not disappear by itself, once found, pay attention to rest, elevate the injection site, promote blood reflux, reduce intravascular pressure, and timely medical care, under the guidance of the doctor, improve the relevant examination, to clarify the cause of the disease, symptomatic treatment.