Sex: M
Vaccine: RSV
Symptoms: Complement factor C4, Complement factor normal, Coombs test negative, Crepitations, Eastern Cooperative Oncology Group performance status
Clinical narrative: respiratory syncytial virus vaccine induced thrombotic microangiopathy/vaccine-induced thrombotic microangiopathy/microangiopathic hemolytic anemia; metabolic encephalopathy; anuric renal failure; multi-organ failure; acute hypoxic respiratory failure; This serious case was reported in a literature article and described the occurrence of thrombotic microangiopathy in a 91-year-old male patient who received RSVPreF3 adjuvanted (Arexvy) for prophylaxis.  Concurrent medical conditions included low back pain, coronary artery disease (status post bypass grafting), coronary artery bypass graft, aortic valve replacement, sick sinus syndrome (status post pacemaker placement), cardiac pacemaker insertion, hypertension, paroxysmal atrial fibrillation, cardiac failure (with preserved ejection fraction), thoracic aortic aneurysm, chronic anemia, prostate cancer stage iv (status post retro pelvic prostatectomy), prostatectomy, radiation therapy, bone metastases (extensive), crackles lung, jugular vein distension, pedal edema, asterixis, ecchymosis (in the left upper extremity), pulmonary edema and urinary retention. Additional patient notes included Patient had not recently started any other new medications or herbal supplements. Concomitant products included abiraterone acetate, prednisone, leuprorelin acetate (Leuprolide Acetate), ELASOMERAN (MODERNA COVID-19 VACCINE), INFLUENZA VACCINE and rituximab.   On an unknown date, the patient received Arexvy. On an unknown date, less than a day after receiving Arexvy, the patient experienced thrombotic microangiopathy (Verbatim: respiratory syncytial virus vaccine induced thrombotic microangiopathy/vaccine-induced thrombotic microangiopathy/microangiopathic hemolytic anemia) (serious criteria hospitalization, GSK medically significant and clinically significant/intervention required), metabolic encephalopathy (Verbatim: metabolic encephalopathy) (serious criteria hospitalization, GSK medically significant and clinically significant/intervention required), anuric renal failure (Verbatim: anuric renal failure) (serious criteria hospitalization, GSK medically significant and clinically significant/intervention required), multi-organ failure (Verbatim: multi-organ failure) (serious criteria hospitalization, GSK medically significant and clinically significant/intervention required) and acute hypoxic respiratory failure (Verbatim: acute hypoxic respiratory failure) (serious criteria hospitalization, GSK medically significant and clinically significant/intervention required). The patient was treated with prednisone. The outcome of the thrombotic microangiopathy and anuric renal failure were resolved and the outcome of the metabolic encephalopathy, multi-organ failure and acute hypoxic respiratory failure were resolving.   The reporter considered the thrombotic microangiopathy, metabolic encephalopathy, anuric renal failure, multi-organ failure and acute hypoxic respiratory failure to be related to Arexvy.     The company considered the thrombotic microangiopathy, metabolic encephalopathy, anuric renal failure, multi-organ failure and acute hypoxic respiratory failure to be related to Arexvy.   Additional Information: GSK Receipt Date 21-AUG-2025.   Author reported a patient presented to hospital with severe low back pain and urinary retention. Patient received the new adjuvant RSV vaccine, known as Arexvy, the day prior at a local pharmacy. His past medical history included coronary artery disease status post bypass grafting, bovine aortic valve replacement, sick sinus syndrome status post pacemaker placement, hypertension, paroxysmal atrial fibrillation, heart failure with preserved ejection fraction, chronic thoracic aortic aneurysm, chronic anemia, and stage IV prostate cancer status post retro pelvic prostatectomy followed by radiation therapy with subsequent recurrence with extensive bony metastases. Pertinent outpatient medications included abiraterone acetate, prednisone (5 mg daily), and leuprolide acetate. Patient had not recently started any other new medications or herbal supplements. Patient had received the coronavirus-19 (COVID-19) Moderna vaccine booster 1 month prior to admission and patient had received the Influenza vaccine 3 weeks prior to admission. Patient had baseline Karnofsky and Eastern Cooperative Oncology Group performance scores of 90 percent and 0, respectively. Patient was found to have metabolic encephalopathy and renal failure. His initial labs showed white blood cell count of 7.7 x 10e9 /L, hemoglobin 12.4 g/dL, and platelet count of 112 x 10e9 /L. His complete metabolic profile was normal, except for a creatinine 1.3 mg/dL, and total bilirubin of 2.2 mg/dL. Baseline labs from seven weeks prior were normal including a hemoglobin of 13 g/dL and a platelet count 201x10e9 /L. His last available total bilirubin three months prior was normal. During his hospitalization, his renal failure (Cr 4.1 mg/dL) and encephalopathy worsened, his hemoglobin and platelets continued to decrease, and his AST increased to 95 U/L with normal ALT at 36 U/L. Due to clinical deterioration with no clear diagnosis. Patient was afebrile with pulse rate 60 bpm, respiratory rate 19/min, blood pressure 191/ 108 mmHg, and acute hypoxic respiratory failure requiring 5 L Oxymask to maintain SpO2 more than 90percent. The physical exam was significant for bibasilar crackles in the lungs, jugular venous distention, trace pedal edema, asterixis, ecchymosis in the left upper extremity, and acute metabolic encephalopathy (Glascow Coma Score 9). Laboratory findings include the following (reference ranges listed parenthetically): hemoglobin, 9 g/dL (13.2-16.6 g/ dL); platelet count, 10 x 10e9 /L (135-317x10e9 /L); white blood cell count, 7.1x10e9 /L (3.4-9.6 x 10e9 /L); creatinine, 5.15 mg/ dL (0.75-1.34 mg/dL); total bilirubin, 2.5 mg/dL (less than 1.2 mg/dL); direct bilirubin, 1.0 mg/dL (0-0.3 mg/dL); lactate dehydrogenase, 3080 U/L (122-222 U/L); D-dimer, 33,652 ng/mL (less than 500 ng/mL); haptoglobin, less than 14 mg/dL (30-200 mg/ dL); immature platelet fraction, 15.7percent (1-7percent). Prothrombin time, activated partial thromboplastin time, and fibrinogen were within normal limits. Soluble fibrin monomer was positive. Complement levels on admission included a normal C3 and C4. Chest x-ray revealed bilateral pulmonary edema. Transthoracic echocardiography (TTE) was obtained to assess for the Waring Blender effect, which revealed no prosthetic or periprosthetic regurgitation. The differential diagnosis on admission for this patient with new-onset microangiopathic hemolytic anemia with anuric renal failure and metabolic encephalopathy included TTP, aHUS, disseminated intravascular coagulation (DIC), Waring-Blender syndrome secondary to paravalvular regurgitation, vaccine-induced thrombotic microangiopathy (TMA), or other causes of TMA. Non-TMA etiologies to explain the thrombocytopenia included vaccine-induced immune thrombotic thrombocytopenia (VITT) and heparin-induced thrombocytopenia (HIT). Heparin platelet factor 4 (PF4) antibody and Coombs test were negative. Peripheral smear revealed schistocytes (more than 10/hpf) and burr cells. ADAMTS13 and aHUS/TMA panels were obtained. Due to concern for TTP with multiorgan failure, plasma exchange (PLEX) and hemodialysis were promptly initiated. Given his stable respiratory status and no severe electrolyte abnormalities, PLEX initiation was prioritized over hemodialysis. After the initial PLEX session, the patient demonstrated significant improvement in mental status. Intermittent hemodialysis and prednisone (60 mg daily) were started subsequently. Rituximab therapy was held pending the ADAMTS13 result. The patient received eight sessions of PLEX in total with complete recovery of mental status to baseline within 48 hours. Prednisone (60 mg daily) was administered daily with PLEX until platelets reached 150x10e9 /L for 3 days, after which steroids were tapered over the next few weeks. ADAMTS13 activity results sent before PLEX returned at 67percent (normal more than 70percent) essentially ruling out a diagnosis of TTP, so rituximab was not administered. AHUS/TMA/complement panel returned with the following lab values: total complement 60 (normal 30-75 U/mL), C3 84 (normal 75-175 mg/dL) C4 28 (normal 14-40 mg/dL), factor B complement antigen 36 (normal 30-75 mg/dL), factor H complement antigen 24.7 (normal 18.5-40.8 mg/dL), alternate complement pathway function more than 110percent (normal more than 46percent), SC5b-9 complement 597 (normal less than 251 ng/dL). CBb complement more than 6 (normal less than 1.7 mcg/dL), and C4d complement 2.7 (normal less than 9.9 mcg/dL). Since this panel was not consistent with active alternative complement pathway activation and given the clinical improvement with PLEX, the patient was not started on eculizumab. On the day of discharge (day 11), platelet count was normal at 267x10e9 /L. By discharge, his renal function had not improved, and patient still required hemodialysis. After discharge, his atypical HUS gene panel results showed a double heterozygote status for CFHR1 exon 2-6 deletion, and CFHR3 exon 1-6 deletion. These specific mutations were not well-characterized and were of unclear clinical significance. After discharge, his clinical status continued to improve. Patient completed his course of prednisone, and his renal function improved to the point that patient came off hemodialysis. His most recent labs at 9 weeks post-discharge showed LDH within normal limits at 188 U/L, Hb of 11.4 g/dL, and platelets of 289x10e9 /L. ALT and AST within normal limits at 27 U/L and 33 U/L, respectively. Total bilirubin within normal limits at 0.5 mg/dL with no indirect hyperbilirubinemia. Creatinine normalized at 0.65 mg/dL. Author presented the case of a patient with microangiopathic hemolytic anemia, anuric renal failure and metabolic encephalopathy within 24 hours of administration of the new Arexvy RSV vaccine. Arexvy RSV vaccine data sheets do not report thrombocytopenia or microangiopathic hemolytic anemias to be known adverse events. The patient was heterozygous for a large deletion involving the CFHR1 and CFHR3 genes, strongly suggesting the presence of a contiguous deletion of the full CFHR1 and CFHR3 genes. Specifically, it was noted that the complement factor H (CFH)-CFHR gene cluster was prone to structural variation resulting in large deletions, duplications, and hybrids of genes within the cluster. Currently, the clinical significance of heterozygous copy number variation impacting the CFHR1 and CFHR3 genes was not well-characterized, and the clinical significance of deletions and duplications impacting other genes within the CFHR cluster was not well-delineated. The patient's complement levels were within normal range, except for elevations in CBb and SC5b-9. These complement-level abnormalities indicate activation of the alternative complement pathway, and in the absence of other complement abnormalities this was most likely secondary to post-blood draw activation. Of note, the expected a-HUS lab findings (low factor H, normal C4 and low AH50) were not present. However, prior studies have reported that complement levels may remain normal in aHUS.4 Classically, aHUS was not effectively treated with PLEX, although it was a first-line treatment for Factor H deficiency. RSV vaccine-induced thrombotic microangiopathy with associated multi-organ failure was a diagnosis of exclusion. High dose corticosteroids with PLEX resolved the patient's microangiopathic hemolytic anemia and thrombocytopenia and, in conjunction with intermittent hemodialysis, resolved the patient's acute renal failure.; Sender's Comments: A case of Thrombotic microangiopathy, Metabolic encephalopathy, Renal failure, Multiple organ dysfunction syndrome and Acute respiratory failure,  less than a day after receiving Arexvy, in a 91-year-old male  patient. Report is consistent with causal relation to the vaccine product, considering plausible time to onset and  etiology (RSV vaccine-induced thrombotic microangiopathy with associated multi-organ failure was a diagnosis of exclusion) based on medical history.