appendix was rotting really quickly / It was super inflammed but getting to the point of bursting; She was in bed for a week; Crying; couldn't stand up straight; I was getting extreme pain in the lower right quadrant of my stomach; tried to sleep and ignore the pain but it got worse/it was hard to lay on the side/was hard to lay down; her arm was a little sore; there was a bump in it; This spontaneous case was reported by a consumer and describes the occurrence of APPENDICITIS (appendix was rotting really quickly / It was super inflammed but getting to the point of bursting) in a 34-year-old female patient who received mRNA-1273 (Moderna COVID-19 Vaccine) (batch no. 002F21A) for COVID-19 vaccination. The occurrence of additional non-serious events is detailed below.     The patient's past medical history included Appendectomy (Patient appendix was rotting really quickly, so underwent emergency surgery.). Concomitant products included ZINC, VITAMIN D NOS, VITAMIN B12 NOS, VITAMIN C [ASCORBIC ACID] and FEXOFENADINE HYDROCHLORIDE (ALLEGRA) for an unknown indication.    On 20-Aug-2021, the patient received first dose of mRNA-1273 (Moderna COVID-19 Vaccine) (unknown route) 1 dosage form. On 20-Aug-2021, the patient experienced VACCINATION SITE PAIN (her arm was a little sore) and VACCINATION SITE SWELLING (there was a bump in it). On 21-Aug-2021, the patient experienced ABDOMINAL PAIN UPPER (I was getting extreme pain in the lower right quadrant of my stomach) and PAIN (tried to sleep and ignore the pain but it got worse/it was hard to lay on the side/was hard to lay down). On 22-Aug-2021, the patient experienced DYSSTASIA (couldn't stand up straight) and CRYING (Crying). On an unknown date, the patient experienced APPENDICITIS (appendix was rotting really quickly / It was super inflammed but getting to the point of bursting) (seriousness criteria hospitalization prolonged and medically significant) and BEDRIDDEN (She was in bed for a week). At the time of the report, APPENDICITIS (appendix was rotting really quickly / It was super inflammed but getting to the point of bursting), ABDOMINAL PAIN UPPER (I was getting extreme pain in the lower right quadrant of my stomach), PAIN (tried to sleep and ignore the pain but it got worse/it was hard to lay on the side/was hard to lay down), DYSSTASIA (couldn't stand up straight) and CRYING (Crying) had resolved and VACCINATION SITE PAIN (her arm was a little sore), VACCINATION SITE SWELLING (there was a bump in it) and BEDRIDDEN (She was in bed for a week) outcome was unknown.        The action taken with mRNA-1273 (Moderna COVID-19 Vaccine) (Unknown) was unknown.       No treatment medication information was mentioned by reporter.  Her physician doesn't think appendicitis was related to the vaccine.  Company Comment: This case concers a 34 year old female patient with no medical history reported, who experience the unexpected event of appendicitis after firs dose of mRNA-1273. The rechallenge was not applicable, as the event happened after the first dose. The event was considered not related to the product as per her physician. The benefit-risk relationship of Spikevax is not affected by this report.; Sender's Comments: This case concers a 34 year old female patient with no medical history reported, who experience the unexpected event of appendicitis after firs dose of mRNA-1273. The rechallenge was not applicable, as the event happened after the first dose. The event was considered not related to the product as per her physician. The benefit-risk relationship of Spikevax is not affected by this report.