underlying autoimmune disease that caused the vascular reaction; rash; underlying autoimmune disease that caused the vascular reaction; This is a spontaneous report from a contactable consumer (Patient Mother). A 15-year-old female patient (Reporter's step-daughter) received bnt162b2 (PFIZER-BIONTECH COVID-19 VACCINE, solution for injection, Lot Number: ER8736), dose 1 via an unspecified route of administration, administered in left upper arm on 15May2021 18:00 as single dose for vaccination. The patient medical history and concomitant medications were not reported. No patient family medical history relevant to AE. No prior Vaccinations within 4 weeks. No history of all previous immunization with the Pfizer vaccine considered as suspect. No additional Vaccines Administered on Same Date of the Pfizer Suspect. Patient broke out with a rash the following Monday evening, 17May2021 causing multiple visits to the Emergency department and Urgent Care Clinics. Reporter and patient are driving to patient's primary care physician's office now. Patient did not get admitted to the hospital. Patient has been to urgent care, and the emergency room a few times. The doctor from the emergency room believe that patient had a vascular reaction to the covid vaccine. The doctor asked reporter to call Pfizer to get some guidance. The doctor thinks that patient has an underlying autoimmune disease that caused the vascular reaction. The doctor put patient on a course of steroids because of patients reaction for whatever is going on. Reporter was looking for guidance about the second dose of the covid vaccine, since patient had this reaction. Reporter is not sure if prednisone will take away the effect of the covid vaccine. Reporter is asking what to do and where to go. Patient was told that she may have had a vascular reaction secondary to a possible underlying immune condition not yet identified. Mom stated that the child was prescribed Prednisone to counter the rash. Mom wanted to know if her child should go ahead and get the second dose of the Pfizer Covid vaccine given the side effects. Patient broke out with a rash was reported as worsened. The patient was advised that she should not get the Pfizer-BioNTech COVID-19 Vaccine if she had a severe allergic reaction after a previous dose of this vaccine had a severe allergic reaction to any ingredient of this vaccine. People with a weakened immune system, including people receiving medications that weaken the immune system (immunosuppressants) were not in the clinical trial for the Pfizer-BioNTech COVID-19; that may have a lower response to the Pfizer-BioNTech COVID-19 Vaccine. The outcome of rash was not recovered and outcome of other events was unknown.  No follow-up attempts are needed. No further information is expected.; Sender's Comments: Based on the information currently available, a possible contributory role of the suspect vaccine BNT162B2 or comirnarty in triggering the onset of autoimmune disorder,vascular disorder,angiopathy cannot be excluded.The impact of this report on the benefit/risk profile of the Pfizer product is evaluated as part of Pfizer procedures for safety evaluation, including the review and analysis of aggregate data for adverse events. Any safety concern identified as part of this review, as well as any appropriate action in response, will be promptly notified to Regulatory Authorities, Ethics Committees and Investigators, as appropriate