ANTICOAGULANT THERAPY; DEEP VEIN THROMBOSIS; MILD HEADACHES; BODY ACHES; PLUS 2 PITTING EDEMA IN THE BILATERAL LOWER EXTREMITIES; DECREASED EXERCISE TOLERANCE; OFF LABEL USE IN AN UNAPPROVED ROUTE OF ADMINISTRATION; This spontaneous report received from a health care professional via a Regulatory Authority (VAERS) Vaccine Adverse Event Reporting System (VAERS ID: 1257659) concerned a 98 year old female. This patient was referenced in literature: The objective of this study is to characteristics of this complication and discuss pertinent changes in patient management when there is concern for adenovirus-vector vaccine-associated VTE after Janssen COVID-19 vaccine administration. The patient's height, and weight were not reported. The patient's past medical history included: invasive ductal breast cancer (was removed with lumpectomy and treated with radiation and tamoxifen therapy completed in 2014. She follows regularly in a breast cancer survivorship program and the most recent bilateral breast ultrasound in January 2021 was negative), and concurrent conditions included: hypertension, osteoporosis, and hepatitis c, and other pre-existing medical conditions included: the patient had no known allergies. She was of normal weight, has never used tobacco products, and did not have a personal nor family history of thrombotic or hemorrhagic disorders, including venous thromboembolism. The patient had an history of a hypercoagulable state, she regularly underwent surveillance to ensure she did not have a recurrence of breast cancer The patient received covid-19 vaccine ad26.cov2.s (suspension for injection, subcutaneous, batch number was not reported) dose was not reported, 1 total administered on 16-MAR-2021 for prophylactic vaccination which was an off label use in unapproved route of administration. Age at time of vaccination 98 years old. The batch number was not reported. Per procedure, no follow-up will be requested for this case. Concomitant medications included simeprevir and sofosbuvir for hepatitis c, alendronate sodium, furosemide, nifedipine, and omeprazole. On an unspecified date, the patient experienced body aches, plus 2 pitting edema in the bilateral lower extremities, and mild headaches. On 05-APR-2021 (20 days post vaccination), the patient experienced decreased exercise tolerance. On 20-APR-2021, the patient experienced deep vein thrombosis, and was hospitalized for one day(date unspecified).On 20-APR-2021, the patient underwent laboratory tests that included Duplex ultrasound acute occlusive DVT in the right proximal-mid femoral and gastrocnemius veins, along with a partially occlusive DVT of the right common and distal femoral veins. Static ultrasound image shows echogenic thrombus in the right femoral vein. Doppler ultrasound image shows lack of blood flow in the right femoral vein due to thrombus. On 21-APR-2021, the patient experienced anticoagulant therapy. The patient visited emergency room or department for treatment of the event. More extensive hypercoagulable workup, including anti-heparin antibodies, antiphospholipid antibody studies, and factor deficiencies, was initially not performed, given this was her first DVT. The patient completed three months of anticoagulation without adverse events or complications. Furthermore, the patient had no other medical incidents, which may have been adverse events secondary to vaccination, such as Bell's palsy, Guillain Barre Syndrome, cerebrovascular accidents, or myocardial infarcts. An echocardiogram was scheduled for the upcoming month. Laboratory data (dates unspecified) included: APTT normal, Anti-platelet factor 4 antibody test normal optical density of 0.04 (reference range: 0.00-0.399 optical density), B-type natriuretic peptide Unspecified, Basic metabolic panel Unspecified, Chest X-ray normal clear lungs (arrows) without pleural effusion or pneumothorax but shallow aspiration, Fibrin D dimer increased 2.17 ug/mL, Fibrinogen within normal limits (336 mg/dL), Hematocrit 39.6 percent (reference range: 36.0-45.0 percent), Hemoglobin 12.2 g/dL (reference range: 11.2-14.7 gm/dL), International normalized ratio normal, Liver function tests normal mild elevation in alkaline phosphatase of 137 (reference range: 38-126 U/L), Physical examination at emergency department revealed unilateral 2 plus pitting edema of the right lower extremity up to the right knee, without associated swelling, erythema, paresthesia, pain, or sensitivity to touch, Platelet count 235 k/uL (reference range 150-400 k/uL), within normal limits (217 k/uL), Polymerase chain reaction negative for COVID-19, Prothrombin time normal, and WBC 4.6 k/uL (reference range: 4.8-10.8 k/uL).  The patient was initially started on one dose of therapeutic enoxaparin was transitioned followed by apixaban for three months. She was then discharged on her second hospital day with a plan to continue standard DVT treatment of anticoagulation for three months with regular primary care follow-up. On arrival at emergency department the patient was hemodynamically stable without fever, hypotension, or tachycardia. The patient denied trauma to the right lower extremity, recent travel, infection (including COVID-19), surgical procedures, or periods of prolonged immobility in the past year. The action taken with covid-19 vaccine ad26.cov2.s was not applicable. The patient had not recovered from deep vein thrombosis, and anticoagulant therapy, and the outcome of body aches, mild headaches, decreased exercise tolerance, plus 2 pitting edema in the bilateral lower extremities and off label use in an unapproved route of administration was not reported. The authors concluded that two African American females aged over 60 years, were found to have VTE within a month of receiving a single-dose adenovirus COVID-19 vaccine. This report was serious (Hospitalization Caused / Prolonged). This case, from the same reporter is linked.  Additional information received from health care professional on 03-JUL-2023. The following information was updated and incorporated into the case narrative: Event added: body aches, decreased exercise tolerance, plus 2 pitting edema in the bilateral lower extremities, off label use in an unapproved route of administration, mild headaches, Product added: simeprevir, Tamoxifen, Lab test: lower extremity duplex ultrasound, basic metabolic panel, b-type natriuretic peptide, chest x ray, physical examination, polymerase chain reaction (pcr) assay, white blood count (wbc), hemoglobin, hematocrit, platelet count, prothrombin time(pt), partial thromboplastin time(ptt), international normalized ratio(inr), liver function tests, platelet count, fibrinogen, anti-heparin (pf4) igg antibodies, d-dimer, Disease added: invasive ductal breast cancer, hepatitis c, event onset date for Deep vein thrombosis (DVT) was updated. Sender's Comments: V1- This follow up version updates- Non-serious event of body aches, decreased exercise tolerance, plus 2 pitting edema in the bilateral lower extremities, off label use in an unapproved route of administration and  mild headaches, event onset date for Deep vein thrombosis (DVT) and  Lab test. MAC updated.  20210514897-Deep vein thrombosis, anticoagulant therapy. Follow-up received regarding Clinical Details. The event has a compatible/suggestive temporal relationship, is unlabeled, and is scientifically plausible. There are other factors more likely to be associated with the event. Specifically: MEDICAL HISTORY. Therefore, this event is considered inconsistent with vaccine administration.