Noticed a significant reduction in herpes simplex outbreaks after the Pfizer COVID vaccination(s)/Reduction of outbreaks around 50~70% less than normal; The initial case was missing the following minimum criteria: (ICH-Unspecified AE). Upon receipt of follow-up information on 12Jan2023 this case now contains all required information to be considered valid.   This is a spontaneous report received from a contactable reporter(s) (Consumer or other non HCP), Program ID:  The reporter is the patient.  A patient (no qualifiers provided) received BNT162b2, BNT162b2 omi ba.4-5 (BNT162B2, BNT162B2 OMI BA.4-5), on 30Sep2022 as dose 4 (booster), single (Lot number: GH9703) intramuscular, in arm for covid-19 immunisation. The patient's relevant medical history included: "Herpes simplex", start date: 1978 (ongoing), notes: Pertinent Details (Include surgical procedures and dates):, Herpes labialis HSV-1, Herpes HSV-2. There were no concomitant medications. Vaccination history included: BNT162b2 (DOSE 3, Anatomical Site of injection: Upper arm, Route of administration: Intramuscular, Batch/Lot number: FE3594), administration date: 16Dec2021, for COVID-19 immunization; Covid-19 vaccine (DOSE 1; unknown manufacturer), for COVID-19 Immunization; Covid-19 vaccine (DOSE 2; unknown manufacturer), for COVID-19 Immunization.  The following information was reported: THERAPEUTIC RESPONSE UNEXPECTED (non-serious), outcome "unknown", described as "Noticed a significant reduction in herpes simplex outbreaks after the Pfizer COVID vaccination(s)/Reduction of outbreaks around 50~70% less than normal".   Additional information: It was reported by the reporter that, "I've noticed an interesting beneficial side effect from your bivalent covid vaccine. I am not looking for anything other than report my experience which may help promote future research. I would be willing to briefly discuss this with a contact with the right person. Noticed a significant reduction in Herpes simplex outbreaks after the Pfizer COVID vaccination(s). Reduction of outbreaks around 50 - 70 % less than normal, if there was a herpes simplex outbreak the duration and severity was lessened. My lifestyle and diet were the same prior to and after vaccination(s). Very beneficial side effects". Patient received the vaccine on Upper arm. Vaccination Facility Type was reported as Hospital. The vaccine was not administered at military facility. There were no other relevant diagnostic and confirmatory test results for event(s), for example, from blood tests, cerebro-spinal fluid culture, pleural fluid culture, urine culture, diagnostic imaging (e.g., chest X-ray, MRI). If COVID-19 testing has been conducted, provide test dates and results. There was no specific relevant test for thromboembolic events with thrombocytopenia.  Follow-up (12Jan2023): This is a spontaneous follow up report from a contactable consumer. This consumer (Patient) reported in response to Non-HCP letter [sent to Non-HCP] via follow-up letter. Updated information included: Reporter slider #01 mail ID added. Patient information updated. As per response historical vaccine coded to COVID-19 vaccine for dose 1 and dose 2 and BNT162B2 for dose 3. RMH (Herpes simplex) was added. Suspect dose information (vaccine start/stop date, dose number, dose description, route and lot) were added. New event (Unexpected therapeutic effect) was added. Concomitant therapy checked as none and additional information was updated.   Follow-up attempts are completed. No further information is expected. Sender's Comments: Linked Report(s): PFIZER INC-PV202300007688 Same reporter/patient/event, different vaccine dose.