Adrenal Crisis in Association With a Febrile Response to the bnt162b2 mRNA COVID-19 (Pfizer)Vaccine; This is a literature report.  A 24-year-old male patient received bnt162b2 (BNT162B2), as dose 2, single (Batch/Lot number: unknown) for covid-19 immunisation. The patient's relevant medical history included: "recurrent nausea" (unspecified if ongoing), notes: 4-month history; "vomiting" (unspecified if ongoing), notes: 4-month history; "severe fatigue" (unspecified if ongoing), notes: 4-month history; "trouble climbing a flight of stairs" (unspecified if ongoing), notes: 4-month history; "weight loss" (unspecified if ongoing), notes: 4-month history. The patient's concomitant medications were not reported. Vaccination history included: Covid-19 vaccine (DOSE 1; MANUFACTURER UNKNOWN), for COVID-19 immunisation. The following information was reported: ADRENOCORTICAL INSUFFICIENCY ACUTE (medically significant, life threatening), 12 hrs after the suspect product(s) administration, outcome "recovering", described as "Adrenal Crisis in Association With a Febrile Response to the bnt162b2 mRNA COVID-19 (Pfizer)Vaccine". The patient underwent the following laboratory tests and procedures: Blood aldosterone (normal high range 16): Less than 3; Blood corticotrophin (7.2-63.3): 1071 pg/mL; Blood cortisol (4.8-19.5): 1.4 ug/dL; Blood pressure measurement: Hypotension persisted despite, notes: aggressive fluid resuscitation and broad-spectrum antibiotics; Blood pressure measurement: 88/42 mmHg; Body temperature: 103 Fahrenheit; Computerised tomogram abdomen: did not identify an etiology for his presentation; Computerised tomogram pelvis: did not identify an etiology for his presentation; Computerised tomogram thorax: did not identify an etiology for his presentation; Heart rate: 100, notes: Unit: bmp on admission; Weight: 40-pound unintentional weight loss. Therapeutic measures were taken as a result of adrenocortical insufficiency acute.  Clinical course: In the face of the COVID-19 pandemic, messenger RNA (mRNA) vaccines were approved for the first time for use in the general population. Vaccination can trigger a febrile flu-like response that was self-limited in healthy individuals. Febrile illness was a classic trigger of acute ad renal insufficiency in patients who are cortisol deficient but recognizing this clinical scenario was challenging in patients with undiagnosed adrenal insufficiency. A 24-year-old male presented to an acute care community hospital with fatigue, fever, and vomiting 12 hours after receiving the second dose of the BNT162b2 mRNA Covid-19 (Pfizer) vaccine. He was 6 feet tall, and his weight was 175 pounds. He had a temperature of 103 F, a blood pressure of 88/42 mmHg, and a heart rate of 100 bmp on admission. Hypotension persisted despite aggressive fluid resuscitation and broad-spectrum antibiotics. CT of the chest and CT angiogram of the abdomen and Pelvis did not identify an etiology for his presentation. Over a period of hours, he became obtunded, disoriented, and required vasopressor support. He received 100 mg of IV hydrocortisone followed by 50 mg every 6 hours for treatment of presumed sepsis and was transferred to an intensive care unit. Within 24 hours of starting glucocorticoid therapy, he was awake and oriented, defervesced, and became normotensive. This rapid improvement led to suspicion of adrenal insufficiency as an underlying diagnosis. Further questioning revealed a 4-month history of recur rent nausea, vomiting, severe fatigue, to the point where he had trouble climbing a flight of stairs, and a 40-pound unintentional weight loss. He visited an emergency department 3 times over this period and had outpatient evaluations by gastroenterology and cardiology without identifying a cause. Inpatient evaluation revealed a morning Cortisol of 1.4 ug/dL (n 4.8-19.5 ug/dL), aldosterone <3 ng/dL (n <16 ng/dL), and ACTH 1071 pg/mL (n 7.2- 63.3 pg/mL) leading to the diagnosis of primary adrenal in sufficiency. He was started on physiologic doses of adrenal replacement hormones and discharged home in stable condition 4 days after his admission date. In conclusion, a severe post-vaccination reaction should elicit physicians to look for an alternative diagnosis. Autoimmune adrenalitis is the most common cause of primary adrenal insufficiency and is uniquely associated with a long lag to diagnosis. The diagnosis is often made in the setting of an intervening illness or physiologic stressor when a patient's condition acutely deteriorates. Patients with known adrenal insufficiency should be reminded to address post-vaccination febrile reactions with an increase in glucocorticoid doses.; Sender's Comments: The event of adrenocortical insufficiency acute is conservatively assessed as related to the suspect drug BNT162B2 based on close temporal association but consider also possible contributory effects from medical history of the patient such as presence of an underlying primary Adrenal Insufficiency. 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.