hospitalization; hypoxia; autoimmune numbers were elevated from inflammation; neck pain that constantly got worse and worse/"it feels like someone is stabbing me in my neck/severe neck pain; condition aggravated; initial pain was throughout his entire body; that he felt like he couldn't breathe; altitude sickness; he couldn't move; inflammation; Initial information was received  on 20-Oct-2023 regarding an unsolicited valid  serious case received from a consumer/non-healthcare professional.  This case is linked to case 2020SA346858(CLUSTER).  This case involves a 69 years old male patient who experienced hospitalization, hypoxia, autoimmune numbers were elevated from inflammation, neck pain that constantly got worse and worse/"it feels like someone is stabbing me in my neck/severe neck pain, initial pain was throughout his entire body, that he felt like he couldn't breathe, altitude sickness, he couldn't move, inflammation after receiving influenza quadrival A-B high dose HV vaccine [Fluzone high-dose quadrivalent].  The patient's past medical history, medical treatment(s), vaccination(s) and family history were not provided.   On an unknown date, the patient received an unknown dose of suspect influenza quadrival A-B high dose HV vaccine (unknown formulation) (lot number, expiry date, strength, was unknown) via unknown route in unknown administration site for prophylactic vaccination  (Immunization). The information on the batch number was requested.  On an unknown date the patient had hospitalization (hospitalisation), hypoxia, autoimmune numbers were elevated from inflammation (autoimmune disorder), neck pain that constantly got worse and worse/"it feels like someone is stabbing me in my neck/severe neck pain (neck pain), symptom of condition aggravated, initial pain was throughout his entire body (pain), that he felt like he couldn't breathe (dyspnoea), altitude sickness (hypobarism), he couldn't move (hypokinesia), inflammation (unknown latency) following the administration of influenza quadrival A-B high dose HV vaccine.  Relevant laboratory test results included: SARS-CoV-2 test - On an unknown date: Negative  Action taken: not applicable.  It was  reported that the patient received an unspecified topical injection for neck pain as a corrective treatment and not reported for other events..  At time of reporting, the outcome was Recovered / Resolved on an unknown date for the event hospitalization, initial pain was throughout his entire body, he couldn't breathe, hypoxia, altitude sickness, he couldn't move, autoimmune numbers were elevated from inflammation, inflammation and was Not Recovered / Not Resolved for the event neck pain that constantly got worse and worse/"it feels like someone is stabbing me in my neck/severe neck pain.  Seriousness Criteria: Medically significant for event hypoxia and autoimmune disorder and Hospitalization.; Sender's Comments: Sanofi Company Comment dated 16-Oct-2023: This case involves a 69 years old male patient who experienced hospitalization,  hypoxia, autoimmune numbers were elevated from inflammation after receiving influenza quadrival A-B high dose HV vaccine [Fluzone high-dose quadrivalent]. Further information on medical history, allergy history, family history, past or concomitant medication excluding alternative etiologies for the reported event are needed to fully assess this case. Based upon the limited reported information, the role of the individual suspect vaccine cannot be assessed.