hypoxemia; dyspnea; BL pulmonary infiltrates; may represent a pneumonitis or other inflammatory process given time course and recurrence; may represent a pneumonitis or other inflammatory process given time course and recurrence; This is a spontaneous report received from a contactable reporter(s) (Physician). A 55 year-old female patient (not pregnant) received bnt162b2 (BNT162B2), administration date 01Dec2021 (Batch/Lot number: unknown) at the age of 55 years as dose 3 (booster), single for covid-19 immunisation. Relevant medical history included: "DM2" (unspecified if ongoing); "diagnosed with mild COVID infection", start date: Dec2020 (not ongoing), notes: completely recovered after 1wk. No Known allergies. Concomitant medication(s) included: METFORMIN. Vaccination history included: Bnt162b2 (Dose Number: 2), administration date: 12Feb2021, when the patient was 54 years old, for Covid-19 immunization, reaction(s): "Hypoxemia", "BL pulmonary infiltrates"; Bnt162b2 (Dose Number: 1), administration date: 25Jan2021, when the patient was 54 years old, for Covid-19 immunization. 2 weeks after second dose subsequently developed hypoxemia and BL pulmonary infiltrates requiring hospital admission, improved with steroids and treatment for CAP. Infectious workup negative. Sx and radiographic findings gradually resolved over 8wks. The following information was reported: HYPOXIA (hospitalization) with onset Dec2021, outcome "recovering", described as "hypoxemia"; DYSPNOEA (hospitalization) with onset Dec2021, outcome "recovering", described as "dyspnea"; LUNG INFILTRATION (hospitalization) with onset Dec2021, outcome "recovering", described as "BL pulmonary infiltrates"; PNEUMONITIS (hospitalization), DISEASE RECURRENCE (hospitalization) all with onset Dec2021, outcome "recovering" and all described as "may represent a pneumonitis or other inflammatory process given time course and recurrence". 3 days after booster dose, developed dyspnea and hypoxemia which progressed over the following week. She was again admitted to hospital with hypoxemia and BL pulmonary infiltrates, again improved with steroids and CAP tx. Concern this may represent a pneumonitis or other inflammatory process related to vaccination given time course and recurrence. The patient was hospitalized for hypoxia, dyspnoea, lung infiltration, pneumonitis, disease recurrence (start date: Dec2021, hospitalization duration: 5 day(s)). The patient underwent the following laboratory tests and procedures: x-ray: (Feb2021) gradually resolved; laboratory test: (2021) negative. Therapeutic measures were taken as a result of hypoxia, dyspnoea, lung infiltration, pneumonitis, disease recurrence included: supplemental O2, steroids, antibiotics.  The lot number for bnt162b2 was not provided and will be requested during follow up.; Sender's Comments: Considering a plausible drug-event temporal relationship, a causal association between the reported events and the suspect product BNT162B2 cannot be completely excluded. Case will be reassessed once with additional information. 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.,Linked Report(s) : US-PFIZER INC-202200238015 same patient and drug, similar event with different dose