Reactivated herpes simplex virus keratitis of the left eye; Reactivated herpes simplex virus keratitis of the left eye; This literature-non-study case was reported in a literature article and describes the occurrence of OPHTHALMIC HERPES SIMPLEX (Reactivated herpes simplex virus keratitis of the left eye) and HERPES SIMPLEX REACTIVATION (Reactivated herpes simplex virus keratitis of the left eye) in a 73-year-old male patient who received mRNA-1273 (Moderna COVID-19 Vaccine) for COVID-19 prophylaxis.   LITERATURE REFERENCE:      The patient's past medical history included HSV infection (Ocular history) and Corneal infection (Patient had ocular history at age 10 in left eye with subsequent scarring. He also reported intermittent irritation of  this eye with any upper respiratory illness).   On 20-Mar-2021, the patient received first dose of mRNA-1273 (Moderna COVID-19 Vaccine) (unknown route) 1 dosage form. On 17-Apr-2021, received second dose of mRNA-1273 (Moderna COVID-19 Vaccine) (unknown route) dosage was changed to 1 dosage form. On 20-Apr-2021,  after starting mRNA-1273 (Moderna COVID-19 Vaccine), the patient experienced OPHTHALMIC HERPES SIMPLEX (Reactivated herpes simplex virus keratitis of the left eye) (seriousness criterion medically significant). On an unknown date, the patient experienced HERPES SIMPLEX REACTIVATION (Reactivated herpes simplex virus keratitis of the left eye) (seriousness criterion medically significant). The patient was treated with VALACYCLOVIR [VALACICLOVIR] (oral) in 2021 at a dose of 1 gram twice a day; TRIFLURIDINE (topical) in 2021 at an unspecified dose and frequency and ERYTHROMYCIN (topical) in 2021 at an unspecified dose and frequency. At the time of the report, OPHTHALMIC HERPES SIMPLEX (Reactivated herpes simplex virus keratitis of the left eye) and HERPES SIMPLEX REACTIVATION (Reactivated herpes simplex virus keratitis of the left eye) had resolved.      DIAGNOSTIC RESULTS (normal ranges are provided in parenthesis if available): In 2021, Slit-lamp examination: of the cornea revealed a 3.5 × 1 mm dendrite with peripheral neovascularization as well as central scarring.     For mRNA-1273 (Moderna COVID-19 Vaccine) (Unknown), the reporter considered HERPES SIMPLEX REACTIVATION (Reactivated herpes simplex virus keratitis of the left eye) to be related. No further causality assessment was provided for OPHTHALMIC HERPES SIMPLEX (Reactivated herpes simplex virus keratitis of the left eye).    No concomitant medications were reported.   The study period was from January 2021 to June 2021. Patient presented with foreign body sensation and photophobia of his left eye for 2 weeks. He also reported intermittent irritation of this eye with any upper respiratory illness. Current episode of irritation began 3 days following his second dose of the Moderna COVID-19 vaccine. The patient was prescribed valacyclovir, trifluridine, and erythromycin and reported resolution of symptoms. Authors hypothesize that the intense immunological reaction following LNP-formulated mRNA-based COVID-19 vaccinations might have triggered or reactivated keratitis. Authors believed that the immunological response following COVID-19 vaccination might explain this phenomenon, though causality could not be proven.  Company comment:This literature-non-study case, concerns a 73-year-old male patient with past ocular history of corneal infection in left eye at age 10 with subsequent scarring, and intermittent irritation of that eye with any upper respiratory illness, ophthalmic herpes simplex infection reported, who experienced the unexpected serious (medically significant) events of Ophthalmic herpes simplex and Herpes simplex reactivation (reported as Reactivated herpes simplex virus keratitis of the left eye) about three days after second dose of mRNA-1273 vaccine in the covid 19 vaccination series. Patient presented with foreign body sensation and photophobia of his left eye for 2 weeks, which began 3 days following  vaccination.. Slit-lamp examination of the cornea revealed a 3.5 × 1 mm dendrite with peripheral neovascularization as well as central scarring. A diagnosis of reactivated herpes simplex virus keratitis of the left eye was made. The patient was prescribed valacyclovir 1 g by mouth twice a day, trifluridine, and erythromycin ointment, and reported resolution of symptoms. The authors concluded that immunological reaction following vaccination might trigger reactivation of keratitis, in this patient having in mind medical history of previous ophthalmic herpes simplex in the left eye. which remains as a confounder for the Reactivated herpes simplex virus keratitis. The benefit-risk relationship of mRNA-1273 Vaccine is not affected by this report.   This case was linked to US-MODERNATX, INC.-MOD-2022-674613, US-MODERNATX, INC.-MOD-2022-674614, US-MODERNATX, INC.-MOD-2022-674615 (Linked Report).; Sender's Comments: This literature-non-study case, concerns a 73-year-old male patient with past ocular history of corneal infection in left eye at age 10 with subsequent scarring, and intermittent irritation of that eye with any upper respiratory illness, ophthalmic herpes simplex infection reported, who experienced the unexpected serious (medically significant) events of Ophthalmic herpes simplex and Herpes simplex reactivation (reported as Reactivated herpes simplex virus keratitis of the left eye) about three days after second dose of mRNA-1273 vaccine in the covid 19 vaccination series. Patient presented with foreign body sensation and photophobia of his left eye for 2 weeks, which began 3 days following  vaccination.. Slit-lamp examination of the cornea revealed a 3.5 × 1 mm dendrite with peripheral neovascularization as well as central scarring. A diagnosis of reactivated herpes simplex virus keratitis of the left eye was made. The patient was prescribed valacyclovir 1 g by mouth twice a day, trifluridine, and erythromycin ointment, and reported resolution of symptoms. The authors concluded that immunological reaction following vaccination might trigger reactivation of keratitis, in this patient having in mind medical history of previous ophthalmic herpes simplex in the left eye. which remains as a confounder for the Reactivated herpes simplex virus keratitis. The benefit-risk relationship of mRNA-1273 Vaccine is not affected by this report. US-MODERNATX, INC.-MOD-2022-674615:54 YO female US-MODERNATX, INC.-MOD-2022-674613:30 YO female US-MODERNATX, INC.-MOD-2022-674614:84 YO female