This is a spontaneous report from an unpublished manuscript. A contactable physician reported for a 53-year-old male patient received bnt162b2 (PFIZER-BIONTECH COVID-19 mRNA VACCINE, Solution for injection, Batch/Lot number was not reported), via an unspecified route of administration on an unspecified date (at unknown age) as single dose for COVID-19 immunisation. Medical history included ILD with autoimmune features. The patient's concomitant medications were not reported. The rapid generation of safe and effective mRNA vaccines has been an unprecedented success of the SARS-CoV-2 pandemic. Adverse events are extremely uncommon even in large population-database analyses. However, exacerbations of underlying hematologic and autoimmune diseases have been reported post-vaccination. Rare cases of possible vaccine-related HLH have also been reported after other SARS-CoV-2 vaccines. Given the widespread administration of these vaccines, it is essential to continue to monitor for rare adverse events and specific patient populations at-risk for them. In this case series, we describe five cases reported across the unknown locations over the last year of hyperinflammatory reactions including HLH with temporal associations to mRNA vaccination in people with underlying immune dysregulation. A 53-year-old man developed interstitial lung disease (ILD) seven-months before presentation. Biopsy showed non-specific interstitial pneumonia. Rheumatologic work-up showed positive anti-Ro/La and U1-RNP autoantibodies. He had no other autoimmune signs or symptoms. Prednisone and mycophenolate were trialed without improvement over four-months. Rituximab was planned, so he received BNT162b2 mRNA-vaccine. Four-days after vaccination, he developed fever and worsening hypoxia. Antibiotics were started, but his symptoms progressed requiring mechanical ventilation. Labs demonstrated new onset pancytopenia, hyperferritinaemia (84848ng/mL), and increased Soluble CD25 (18100U/mL). Bone marrow biopsy showed hemophagocytosis. Infectious evaluation revealed only an EBV viremia (10275-IU/mL) of unknown duration. He was started on dexamethasone, anakinra, and intravenous immunoglobulin. On transfer he was consented onto study (unknown) #. His condition improved over eight-weeks but was complicated by Pseudomonas bacteremia and autoimmune hemolytic anemia (AIHA). Ventilatory support was weaned after three-months, and he was discharged to a rehabilitation facility. The patient was 53-year-old man with Underlying Condition ILD with autoimmune features. Lab test included: Temperature (Celsius): 39.6, Ferritin (ng/mL): 75249, White blood count (K/uL): 3.0, Hemoglobin (g/dL): 11.5, Platelet (K/uL): 11.5, Triglycerides (mg/dL): 263, Fibrinogen (mg/dL): 435, AST (U/L): 98, 1007. Soluble CD25 (pg/mL): 18,100, Hemophagocytosis: Yes, H-Score: 213. EBV blood PCR (IU/mL): 10275. Vaccine Response- anti-spike antibody (U/mL): Positive-15.7. Organomegaly: Hepatomegaly. Treatment included: Dexamethasone, IVIG, anakinra. The Outcome of the events worsening hypoxia, fever was recovering, for other events was unknown.  The lot number for the vaccine, [BNT162B2], was not provided and will be requested during follow up.; Sender's Comments: Based on the temporal relationship, the association between the events autoimmune hemolytic anemia, bacterimia, hemophagocytic lymphohistiocytosis, hypoxia, AST increased, and pancytopenia 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.