IMMUNE SYSTEM RESPONSE; THERAPEUTIC RESPONSE DECREASE; FIBRIN D-DIMER ELEVATED; NEUROLOGICAL REACTION FOCUSED ON HIS FACE AND HEAD; WEIGHT LOSS; This spontaneous report received from a consumer (father) concerning his son, a 24 year old male of unspecified race and ethnicity. Initial report was processed with additional information received on 09-JUN-2021 from a consumer (mother). The patient's weighed 162 pounds and was 6 feet tall; medical history included a few previous headaches, as a young child the patient had nose bleeds and seasonal allergies. He tested allergic to mold and dust (currently very mild if at at); reported as "otherwise healthy". The patient, at age 23, received covid-19 vaccine ad26.cov2.s (suspension for injection, route of admin, and batch number were not reported) dose was not reported, administered on 11-APR-2021 for prophylactic vaccination. No concomitant medications were reported.  The patient on Sunday evening of 11-APR-2021 after receiving the vaccine had a fever and headache. The fever resolved on the second day but the headache remained at a similar level until Wednesday 14-APR-2021 when it became vice like. He experienced nonstop facial and head pain and pressure. The patient had pain in the bridge of his nose that intensified regularly and pain radiated below his temples, around his ears and has sporadically occurred in other parts of his head. He has had pressure on both temples and elsewhere that felt like a vice although which has subsided.  His mother reported the gnawing pain was difficult for him to deal with.  The patient reported he never had experienced head pain of this type previously.  On 19-APR-2021 the patient received the following laboratory test of a complete blood count as follows: white blood cell count (WBC) (NR: 4 - 11 10*3/mm3) 4.0; red blood cell count (RBC) (NR: (4.0 - 6.2 10*6/mm) 4.72; hemoglobin (HGB) (NR 11 - 18.8 g/dl) 13.8; hematocrit (NR 33-55%) 41; mean cell volume (MCV) (NR: 80 - 100 um3) 87; mean cell hemoglobin (MCH) (NR: 26-24 pg) 29.3; mean cell hemoglobin concentration (MCHC) (NR:(31.0 - 35 g/dl) 33.6; red cell distribution width (RDW) (NR: (10 - 20 %) 12.6; platelets (PLT) (NR:(150 - 400 10*3/mm) 150. On an unspecified date, laboratory results showed the patient was negative to the Coronavirus. On 21-APR-2021 the patient received a brain magnetic resonance imagining (MRI) without contrast with results of no evidence of intracranial hemorrhage, fluid collection, or mass lesions. Mild mucoperiosteal thickening of the paranasal sinus disease. As this was the only clinical indication the physicians felt the patient had a sinus infection and treated him with two different antibiotics which had no effect. A lumbar puncture was not performed. A comprehensive metabolic panel was drawn on 06-MAY-2021 with the significant for the following elevated results: Calcium (NR:8.4 - 10.2 mg/dL) 10.3; total protein (NR: 5.9 - 8.1 g/dL) 9.2; albumin (NR:3.5 - 5.0 g/dL) 5.5. The patient received a repeat complete blood count on 06-MAY-2021 as follows: WBC (NR: 4.50 - 11.00 K/cu mm) 6.91; RBC (NR:4.50 - 5.90 M/cu mm) 5.18: HGB (NR:13.9 - 16.3 g/dL) 14.8; hematocrit (NR: 41.0 - 53.0 %) 45.1%; MCV (NR:80.0 - 100.0 fL) 97.1; MCH (NR:26.0 - 34.0 pg) 28.6; MCHC (NR:31.0 - 37.0 g/dL) 32.8; RDW (NR: 11.5 - 14.5 %) 11.9; PLT (NR:150 - 350 K/cu mm) 156; mean platelet volume (NR:9.2 - 12.7 fL) 12.4.   On 07-MAY-2021 another brain MRI was performed with and without contrast and MRI venogram which showed a normal brain MRI, no cause for headache seen, no sinus thrombosis, no hemorrhage, cerebral edema, mass or acute cortical infarction, there was opacification of the right frontal sinus and bilateral anterior ethmoid sinuses - correlate for sinusitis as a cause for headache.  The Ears, Nose and Throat (ENT) immunology specialist, ruled out a sinus infection and sent him for a CT scan which came back normal (dates unspecified). On 13-MAY-2021 the physician ordered a series of blood work: SARS-CoV-2 IgM Antibody: negative; SARS-CoV-2 IgG Antibody: negative; Fibrin D-Dimer (NR 0.00-0.49 mg/L FEU) 2.40 (Fibrin D-Dimer elevated); SARS-CoV-2 Semi-Quant Antibody (NR:<0.8 U/mL) 18.2 (therapeutic response decreased).  The physician told the patient his neutralizing antibody was very low about 31% which indicated a minimal antibody response to the vaccine. The physician felt the patient was having an immune response to the adenovirus (immune rejection of the virus which triggered a series of immune reactions and less likely to be reactions to the S protein of COVID. Gabepentin for the pain starting at 100 mg twice a day, increased to 200 mg but the dose did not affect the pain.  The physician recommended the patient receive another vaccine from a different pharmaceutical company once his current symptoms go away.  The physician would then test the patient's antibodies after a first shot to see if he requires a second.  The patient also saw an internist (date unspecified) who stated as the patient was physically a big man, he would need a higher dose of gabepentin and raised the dose to 300 mg three times a day and was later raised to 600 mg three times a day.  The ENT physician then raised gabepentin again to 900 mg three times a day; and informed the patient the pain would go away when his immune system calms down. The ENT also stated that when the patient's pain was gone maybe he should go straight to the booster shot for a vaccine to COVID 19. On an unspecified date, the patient saw a neurologist who said that the patient's events were caused by an immunological reaction to the vaccine; which caused a neurological reaction focused on his face and head.   His mother stated "the doctors who have seen him all have the belief that his head pain is a reaction to the vaccine." The mother also reported there were no clinically relevant abnormalities found in the testing. The gabepentin currently has given very little relief from the pain and pressure for the patient, which becomes worse at night. The patient was frustrated that the medications have not really worked and was afraid he won't get ever get better. He occasionally awakens headache free but after 30 minutes the symptoms were back. He has not had a pain free day in 2 months which was affecting his quality of life. No unconventional therapies have been attempted. The patient has also lost 20 pounds in the past 2 months since he received the vaccine. The action taken with covid-19 vaccine ad26.cov2.s was not applicable. The patient had not recovered from neurological reaction focused on his face and head, immune system response and weight loss; the outcome of Fibrin D-Dimer elevated and therapeutic response decrease was unknown. This report was serious (Other Medically Important Condition).; Sender's Comments: V0: This spontaneous report received from a consumer's parents concerning their son, a 24-year-old man, who experienced "neurological reaction on face/head" and "immune system response" associated with weight loss. Medical history included a few previous headaches, and as a young child the patient had nose bleeds and seasonal allergies. No concomitant medications were reported. The evening on the same day after vaccine had a fever and headache. The fever resolved on the day 2 but the headache remained at a similar level through day 3 when it became vice-like, associated with persistent facial and head pressure, and nasal bridge pain radiating bitemporally. The patient has also lost 20 pounds since receiving vaccine. The patient underwent two magnetic resonance imaging (MRI) (without and with contrast) and a computed tomography (CT) scan to rule out blood clots. The results were negative except for findings of some thickening around the nasal area in the MRIs which led two doctors to consider a sinus infection; he was treated with two different antibiotics without relief and the Ear, Nose and Throat (ENT) immunology specialist ruled out a sinus infection. Labs showed a borderline platelet count of 150,000 and an elevated D dimer (2.4), with no anti-PF4 performed. A lumbar puncture was not performed. The physician felt there may be an allergic reaction to the Adenovirus shell of the vaccine. Gabapentin was initiated at escalating doses with very little relief. A neurologist said that the patient's events were caused by an immunological reaction to the vaccine. A physician stated the pain could be treated but the "cause" will only go away only when the patient's immune system calms down. Although there is a close temporal relationship, there is limited information to establish a definitive causal associated with vaccine. Additional information has been requested to guide further assessment.