severe-unremitting headache; This literature-non-study case was reported in a literature article and describes the occurrence of HEADACHE (severe-unremitting headache) in a 31-year-old male patient who received mRNA-1273 (Moderna COVID-19 Vaccine) for COVID-19 vaccination.       Concurrent medical conditions included Hemicrania (Hemicrania continua well controlled on indomethacin. Formerly misdiagnosed with childhood migraine headaches, with increasing severity and duration until 28 years old, when use of indomethacin led to complete symptom resolution.).    On an unknown date, the patient received second dose of mRNA-1273 (Moderna COVID-19 Vaccine) (unknown route) 1 dosage form. On an unknown date,  after starting mRNA-1273 (Moderna COVID-19 Vaccine), the patient experienced HEADACHE (severe-unremitting headache) (seriousness criterion medically significant). The patient was treated with INDOMETHACIN [INDOMETACIN] for Hemicrania, at an unspecified dose and frequency; RIZATRIPTAN for Hemicrania, at an unspecified dose and frequency; FREMANEZUMAB for Hemicrania, at an unspecified dose and frequency; KETOROLAC for Hemicrania, at an unspecified dose and frequency; LEVOBUPIVACAINE for Hemicrania, at an unspecified dose and frequency and DEXAMETHASONE for Hemicrania, at an unspecified dose and frequency. At the time of the report, HEADACHE (severe-unremitting headache) had resolved.      DIAGNOSTIC RESULTS (normal ranges are provided in parenthesis if available): On an unknown date, Magnetic resonance imaging: normal No intracranial pathology.. On an unknown date, Physical examination: abnormal Left-sided conjunctival injection, lacrimation, ptosis, facial flushing and swelling..     For mRNA-1273 (Moderna COVID-19 Vaccine) (Unknown), the reporter considered HEADACHE (severe-unremitting headache) to be related.    Concomitant medications not reported. After vaccine patient had headache and was described as shocking and throbbing, 10/10 severity, radiating to left temporal, maxillary molars, and auricular areas, worse with sudden movements, with no relieving factors, associated with disrupted daily activities. Headache was unresponsive to indomethacin after receiving COVID-19 vaccine. Trials of rizatriptan, steroids, ketorolac, and fremanezumab were unsuccessful. Minor pain relief obtained with greater occipital nerve block using levobupivacaine and dexamethasone.  Company comment: This literature non-study case concerns a 31-year-old male patient with a relevant medical history of hemicrania continua previously well controlled on indomethacin, who experienced the unexpected serious event of Headache after mRNA- 1273 Moderna vaccine. The onset of the event occurred approximately 5 hours after the second dose of mRNA- 1273 vaccine and had a duration of over 60 days. Headache was described as shocking and throbbing, 10/10 severity, radiating to left temporal, maxillary molars, and auricular areas, worse with sudden movements, with no relieving factors, associated with disrupted daily activities. Physical exam showed left-sided conjunctival injection, lacrimation, ptosis, facial flushing and swelling.  Magnetic resonance imaging was normal. Treatment with Indomethacin, Rizatriptan, Steroids, Ketorolac, and Fremanezumab were unsuccessful. Greater occipital nerve block using levobupivacaine and dexamethasone was performed, with minor pain relief. Previous history of Hemicrania continua remains a confounder. Non serious event of headache is consistent with the known safety profile of the vaccine, but due to the severity, duration and resistance to multiple treatments, headache is considered serious and unexpected. The benefit-risk relationship of mRNA- 1273 vaccine is not affected by this report.; Sender's Comments: This literature non-study case concerns a 31-year-old male patient with a relevant medical history of hemicrania continua previously well controlled on indomethacin, who experienced the unexpected serious event of Headache after mRNA- 1273 Moderna vaccine. The onset of the event occurred approximately 5 hours after the second dose of mRNA- 1273 vaccine and had a duration of over 60 days. Headache was described as shocking and throbbing, 10/10 severity, radiating to left temporal, maxillary molars, and auricular areas, worse with sudden movements, with no relieving factors, associated with disrupted daily activities. Physical exam showed left-sided conjunctival injection, lacrimation, ptosis, facial flushing and swelling.  Magnetic resonance imaging was normal. Treatment with Indomethacin, Rizatriptan, Steroids, Ketorolac, and Fremanezumab were unsuccessful. Greater occipital nerve block using levobupivacaine and dexamethasone was performed, with minor pain relief. Previous history of Hemicrania continua remains a confounder. Non serious event of headache is consistent with the known safety profile of the vaccine, but due to the severity, duration and resistance to multiple treatments, headache is considered serious and unexpected. The benefit-risk relationship of mRNA- 1273 vaccine is not affected by this report.