mental confusion; Cognitive confusion; aches; fever; chills; muscle pain; headache; unexpected benefits; Revaccination with different COVID-19 vaccine; Interchange of vaccine products; This spontaneous case was reported by a consumer and describes the occurrence of CONFUSIONAL STATE (mental confusion), COGNITIVE DISORDER (Cognitive confusion), PAIN (aches), PYREXIA (fever) and CHILLS (chills) in an adult female patient who received mRNA-1273.815 (SPIKEVAX 2023-2024) (batch no. ASKU) for COVID-19 prophylaxis. The occurrence of additional non-serious events is detailed below.     Previously administered products included for Product used for unknown indication: Pfizer (EN6207) on 15-Apr-2021, Pfizer (ER8729) on 05-May-2021 and Pfizer (FL3197) on 23-Nov-2022. Past adverse reactions to the above products included No adverse event with Pfizer, Pfizer and Pfizer. Concurrent medical conditions included Penicillin allergy and Sulfonamide allergy (Sulfa drugs).    On 28-Sep-2023, the patient received fifth dose of mRNA-1273.815 (SPIKEVAX 2023-2024) (unknown route) .5 milliliter. On an unknown date, the patient experienced CONFUSIONAL STATE (mental confusion), COGNITIVE DISORDER (Cognitive confusion), PAIN (aches), PYREXIA (fever), CHILLS (chills), MYALGIA (muscle pain), HEADACHE (headache), THERAPEUTIC RESPONSE UNEXPECTED (unexpected benefits), COVID-19 IMMUNISATION (Revaccination with different COVID-19 vaccine) and INTERCHANGE OF VACCINE PRODUCTS (Interchange of vaccine products). At the time of the report, CONFUSIONAL STATE (mental confusion), COGNITIVE DISORDER (Cognitive confusion), PAIN (aches), PYREXIA (fever), CHILLS (chills), MYALGIA (muscle pain), HEADACHE (headache), THERAPEUTIC RESPONSE UNEXPECTED (unexpected benefits), COVID-19 IMMUNISATION (Revaccination with different COVID-19 vaccine) and INTERCHANGE OF VACCINE PRODUCTS (Interchange of vaccine products) outcome was unknown.        For mRNA-1273.815 (SPIKEVAX 2023-2024) (Unknown), the reporter did not provide any causality assessments.   Concomitant product use was not provided by the reporter.  The patient wanted to provide feedback for the booster 50mcg Spikevax that she received. Patient's states, wanted to provide the feedback because she had a very good experience with a booster. She's had two covid shots, followed by 2 boosters and this was her third booster. Patient reported that she noticed about Moderna product in comparison to the other products seemed to be a much stronger reaction. It appeared to be a much more well-designed immune reaction in that the previous shots that she got which gave her general symptoms. She went on to say, but in the case of Moderna drug every 4 hours, it introduced a new set of symptoms and she saw that immune system was responding to each type of symptoms that people get when they get covid over the course of about 2 days. Patient stated that she felt that it was more effective and tailored response than she would experience before and felt compelled to provide the feedback. Patient's each symptom was introduced separately, which she believed was an indication that Moderna drugs are a little bit more cutting edge. Patient stated that she did not know how to all of this in a file but thought it was useful to provide the positive feedback. Patient explained that every 4 hours she experienced a symptom, first it was fever, followed by chills, then aches and pains, muscle pain, headache, and cognitive fog, cognitive confusion, and a couple of others which she couldn't recall. Patient reported that it was not the typical random immune reaction. It felt like it was well designed to introduce her immune system. Patient reported that she was one of the first people in her region to get the booster.  Treatment information was not provided.   Most recent FOLLOW-UP information incorporated above includes: On 20-Oct-2023: Live Follow-up information received included added Events, Products details and updated narrative.