Anemic; Fever of 103ºF perhaps higher because of the chills; Fever of 103ºF perhaps higher because of the chills; High/Elevated lactic acid; The patient does not remember anything/Amnesica (she didn't remember getting the flu shot); Got confused; This spontaneous case was received on 01-Sep-2020 from a physician via agency (reference number SEQW-01120) and concerned a 66-year-old, female patient.  The patient's concurrent conditions included high blood pressure and diabetes. The patient had no known allergies. The patient's concomitant medications included metformin and lisinopril, both used for unreported indications. It was reported that patient got vaccinated with other vaccines in the past years and she had no adverse events.   On 31-Aug-2020, the patient was vaccinated with Flucelvax QIV (influenza vaccine, subunit influenza virus vaccine polyvalent, dose: 0.5 ml, route of administration: intramuscular, anatomical location: deltoid) for flu prevention. The batch number reported was 10283849, expiry date: 30-Jun-2021.   On the same day, four hours after receiving Flucelvax QIV, the patient developed fever of 103 degrees Fahrenheit (F), perhaps higher because of the chills. The patient was advised to go to the emergency room (ER) for medical assistance. The patient got confused and amnesica (as reported) (she didn't remember getting the flu shot).   On 31-Aug-2020, the patient was admitted to the hospital. At the hospital she had been given intravenous (IV) fluids.   On the same date, a lab test revealed high/elevated lactic acid.    On 01-Sep-2020, the patient was found to be a little anemic. The patient was still confused and did not remember anything from yesterday.   At the time of initial reporting on 01-Sep-2020, the patient did not recover from the events and was still at the hospital.   The reporter assessed the events to be related to Flucelvax QIV. Physician stated that she did not feel Flucelvax Quadrivalent is safe and because of that she wanted to return the vaccines she had bought, after a serious adverse event on her patient following administration of the product.   The reported assessed the events as serious due to hospitalization.  Company comment: Blood lactic acid increased, amnesia, confusional state, anaemia, chills and pyrexia were associated with the use of the suspect product Flucelvax QIV for flu prevention. The events: chills, pyrexia, amnesia and confusional state occurred 4 hours after vaccination making chronology highly suggestive, while for remaining events was assessed as plausible, except for anaemia for which temporal association is unsuggestive. The patient's concurrent conditions included high blood pressure and diabetes while concomitant medications included metformin and lisinopril, both used for unreported indications. It was reported that patient got vaccinated with other vaccines in the past years and she had no adverse events. With information presented, causality is assessed as possibly related for pyrexia, unlikely related for chills since pyrexia was present. For amnesia, confusional state and blood lactic acid increased causality is assessed as unrelated due to reported diabetes. Uncontrolled diabetes may increase the risk of experiencing cognitive problems, such as memory loss. Higher than normal blood glucose levels can damage nerve cells, supportive glial cells, and blood vessels in both peripheral nerves of the body and the brain. Causality for anaemia is also assessed as unrelated due to unsuggestive temporal association and reported diabetes and concomitant drugs. (''unlikely related'' defaults to "related" in the safety database for reporting purposes); Reporter's Comments: Physician stated that she did not feel Flucelvax Quadrivalent is safe and because of that she wanted to return the vaccines she had bought, after a serious adverse event on her patient following administration of the product.; Sender's Comments: Blood lactic acid increased, amnesia, confusional state, anaemia, chills and pyrexia were associated with the use of the suspect product Flucelvax QIV for flu prevention. The events: chills, pyrexia, amnesia and confusional state occurred 4 hours after vaccination making chronology highly suggestive, while for remaining events was assessed as plausible, except for anaemia for which temporal association is unsuggestive. The patient's concurrent conditions included high blood pressure and diabetes while concomitant medications included metformin and lisinopril, both used for unreported indications. It was reported that patient got vaccinated with other vaccines in the past years and she had no adverse events. With information presented, causality is assessed as possibly related for pyrexia, unlikely related for chills since pyrexia was present. For amnesia, confusional state and blood lactic acid increased causality is assessed as unrelated due to reported diabetes. Uncontrolled diabetes may increase the risk of experiencing cognitive problems, such as memory loss. Higher than normal blood glucose levels can damage nerve cells, supportive glial cells, and blood vessels in both peripheral nerves of the body and the brain. Causality for anaemia is also assessed as unrelated due to unsuggestive temporal association and reported diabetes and concomitant drugs. (''unlikely related'' defaults to "related" in the safety database for reporting purposes)