Fever; Tachycardia; Hypotension; acute on chronic hypoxic respiratory failure; acute exacerbation of chronic obstructive pulmonary disease; This is a solicited report from from a contactable physician and other health professional based on the information received by Pfizer (Manufacturer Control No: UNT-2021-009438).   A 71-year-old male patient received BNT162B2 (PFIZER-BIONTECH COVID-19 VACCINE), via an unspecified route of administration, on 26Apr2021 (Batch/Lot number was not reported), as dose 1, single, for COVID-19 immunisation; and treprostinil sodium (TYVASO Inhalation gas), via respiratory inhalation, from 08Feb2021 (Batch/Lot Number: 2101925; Expiration Date: 31Jan2022), at 18-54 ug, four times a day, for primary pulmonary arterial hypertension (Pulmonary arterial hypertension). Medical history included pulmonary arterial hypertension, rhinitis allergic, arteriosclerosis coronary artery, coronary artery disease, basal cell carcinoma (cheek), chronic kidney disease, coagulopathy, chronic obstructive pulmonary disease (2 years), diaphragmatic hernia, deep vein thrombosis (after knee surgery; 3 clots in calf of right leg), factor V Leiden carrier, gastrooesophageal reflux disease, nephrolithiasis, essential hypertension, hyperlipidaemia, liver disorder (liver abscess with resection (partial resection in 2007) due to strep infection), osteoarthritis, supraventricular tachycardia, type 2 diabetes mellitus (without complication and without long term current use of insulin), stress (to some extent), benign prostatic hyperplasia, umbilical hernia, arthritis, aortic valve incompetence, aortic disorder, aortic dilatation, iga nephropathy, nephrolithiasis, sleep apnoea syndrome, bicuspid aortic valve, pain, wheezing, prostatomegaly, neck pain, oral disorder, illness, liver abscess, sepsis, transaminases increased, dyspnoea, hydrocele operation, dependence on oxygen therapy, all from unspecified dates and ongoing; neoplasm malignant in 2014 and ongoing; colon operation in 1985; abdominal operation in Feb2007 (Liver resection due to abscess); cholecystectomy in Feb2017; pneumonia bacterial in 2010; coronary angioplasty in May2011; cardiac ablation on 06Mar2017; central venous catheterization on 01Dec2018; stent placement on 11May2021 (insertion of non-drug eluting coronary artery stent); knee operation/knee surgery on an unspecified date; pneumonia on an unspecified date; pulmonary embolism on an unspecified date; hepatectomy on an unspecified date; COVID-19 on an unspecified date; ex-tobacco user from 01Jan1076 to 31Dec2006 (Pks/days: 1.50, Yrs: 30.00, Pk yrs: 45:00, Yrs since quitting: 14.4); primary pulmonary arterial hypertension (Pulmonary arterial hypertension), arteriosclerotic heart disease, nonrheumatic aortic valve insufficiency, shortness of breath, and febrile illness from unspecified dates Concomitant medications included allopurinol (ZYLOPRIM Tablet 100 mg), amlodipine besilate (NORVASC Tablet 5 mg), doxazosin mesylate (CARDURAN Tablet 2 mg), fluticasone furoate, umeclidinium bromide, vilanterol trifenatate (TRELEGY ELLIPTA), furosemide (LASIX Tablet 40 mg), hydralazine hydrochloride (APRESOLINE Tablet 100 mg), metformin hydrochloride (GLUCOPHAGE Tablet 1000 mg), pantoprazole sodium sesquihydrate (PROTONIX Tablet 40 mg), simvastatin (ZOCOR Tablet 10 mg), all from 23Mar2021 and ongoing; amlodipine besilate and acetaminophen tablet both from unspecified dates, salbutamol sulfate (VENTOLIN HFA) from 07Dec2020, acetylsalicylic acid (ASPIRIN Chewable tablet 81 mg) from 14May2019, fexofenadine hydrochloride (ALLEGRA Tablet 180 mg) from 09Feb2015, fluticasone propionate (FLONASE) from 24May2017, guaifenesin (MUCINEX Tablet 600 mg) from 05Nov2019, saccharomyces boulardii (FLORASTOR Capsule 250 mg) from 26Oct2020, all ongoing; salbutamol (PROVENTIL) from 30Mar2021; losartan potassium (COZAAR Tablet 100 mg) from 23Mar2021, glyceryl trinitrate (NITROGLYCERINE) and oxygen from unspecified dates. The patient previously took rivaroxaban (XARELTO) as anticoagulant therapy and experienced anaphylactic reaction (drug hypersensitivity); ibuprofen and experienced drug hypersensitivity (told not to take after stent put in May); morphine for pain and experienced drug hypersensitivity; ceftriaxone sodium (ROCEPHIN) for pruritus and experienced drug hypersensitivity and rash (tolerates penicillins). Historical vaccines included Pneumococcal vaccine polysacch 23v in 18Jan2007 at age 57 years old and on 30Apr2018 at age 68 years old for immunization; Influenza vaccine on 27Sep2011 at age 62 years old, on 10Jan2013 at age 63 years old, on 12Nov2013 at age 64 years old, 16Oct2014 at age 65 years old, 10Nov2015 at age 66 years old, 14Nov2016 at age 67 years old, 25Sep2017 at age 68 years old, 29Oct2018 at age 69 years old, 13Sep2019 at age 70 years old for immunization; Tdap on 17Oct2011 at age 62 years old and on 20Oct0218 at age 69 years old for immunization; Zoster on 30Jul2012 at age 63 years old for immunization; Pneumococcal vaccine 13v on 10Aug2015 ag age 66 years old for immunization; Quadrivalent Influenza vaccine on 08Sep2020 at age 71 years old for immunization. On 29Apr2021, the patient experienced fever, tachycardia, hypotension, acute on chronic hypoxic respiratory failure and acute exacerbation of chronic obstructive pulmonary disease. All events resulted to hospitalization (as reported). The patient was admitted for the evaluation of fever, tachycardia, and hypotension that started 24 to 48 hours after he had received first COVID-19 Pfizer vaccine on 26Apr2021. He received 1 liter of IV fluid bolus and Tylenol (paracetamol). The patient had had mild acute on chronic hypoxic respiratory failure and was placed on nasal cannula. He received solumedrol (methylprednisolone) 3 times doses. His computed tomography angiography (in 2021) revealed no evidence of pulmonary embolism or pneumonia. It was reported that the patient had an injection in his neck on 12Apr2021. On 01May2021 at 11:45, the blood pressure was 124/82 mmHg, pulse rate 71 beats/min, respiratory rate 18/min, temperature 36.7 degree Celsius, and SpO2 was 96 %. The patient improved progressively and remained hemodynamically stable. His blood culture was negative at 48 hours was discharged with a portable oxygen. On 24May2021, the patient had physician office visit for COPD, where it was reported that the patient received 2nd COVID-19 vaccine dose 7 days ago (17May2021) and felt very fatigued with some fevers for 3 days. The patient was doing better at the time of office visit. The review of system was positive for shortness of breath. The pulmonary physical examination revealed rales from right and left-lower fields. There was no Tachypnoea or respiratory distress. The cardiovascular physical examination revealed normal rate, regular rhythm, and normal pulses. The vitals examination revealed blood pressure 140/70 mmHg, pulse rate 87 beats/min, respiratory rate 16 /min, temperature 36.7 degree Celsius, and SpO2 was 95 %.  The action taken in response to the events for treprostinil sodium was unknown. The patient recovered from fever on 20May2021 and was recovering from the remaining events.  Case Comment/Senders Comment: The company has assessed the serious adverse event of acute respiratory failure, chronic obstructive pulmonary disease, tachycardia, hypotension and pyrexia as not related to IH treprostinil and TD-300/A device. Acute respiratory failure, chronic obstructive pulmonary disease were likely due to exacerbation of underlying PAH and COPD. Pyrexia, tachycardia, hypotension were possibly a reaction to Pfizer BioNTech COVID-19 vaccine.  The reporter's assessment of the causal relationship of all events with the suspect product was not provided at the time of this report. Since no determination has been received, the case is managed based on the company causality assessment.  Information on the lot/batch number has been requested.; Sender's Comments: There is no reasonable possibility that the events acute respiratory failure and COPD exacerbation were related to BNT162b2. These are more likely associated with the underlying PAH and COPD. Based on the temporal relationship, the association between the events fever, tachycardia, and hypotension with BNT162b2 can not be fully 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.