No Adverse event; Received 0.25 ml of bivalent dose instead of 0.5 ml; This spontaneous case was reported by an other health care professional and describes the occurrence of ACCIDENTAL UNDERDOSE (Received 0.25 ml of bivalent dose instead of 0.5 ml) and NO ADVERSE EVENT (No Adverse event) in a 50-year-old female patient who received mRNA-1273 BIVALENT .222 (MODERNA COVID-19 VACCINE, BIVALENT (ORIGINAL AND OMICRON BA.4/BA.5)) (batch no. AS7143C) for COVID-19 prophylaxis.     No Medical History information was reported.    In 2022, the patient received dose of mRNA-1273 BIVALENT .222 (MODERNA COVID-19 VACCINE, BIVALENT (ORIGINAL AND OMICRON BA.4/BA.5)) (unknown route) .25 milliliter. In 2022, the patient experienced ACCIDENTAL UNDERDOSE (Received 0.25 ml of bivalent dose instead of 0.5 ml). On an unknown date, the patient experienced NO ADVERSE EVENT (No Adverse event). At the time of the report, ACCIDENTAL UNDERDOSE (Received 0.25 ml of bivalent dose instead of 0.5 ml) and NO ADVERSE EVENT (No Adverse event) outcome was unknown.        For mRNA-1273 BIVALENT .222 (MODERNA COVID-19 VACCINE, BIVALENT (ORIGINAL AND OMICRON BA.4/BA.5)) (Unknown), the reporter considered NO ADVERSE EVENT (No Adverse event) to be not related. No further causality assessment was provided for ACCIDENTAL UNDERDOSE (Received 0.25 ml of bivalent dose instead of 0.5 ml).    No concomitant medications were provided. Reporter saw that the dosage was changed to 0.5 ml. For the past month, reporter had been giving 0.25 ml. 19 patients received the half doses on 15-Sep-2022, 22-Sep-2022, 29-Sep-2022 and 06-Oct-2022. No treatment medication was provided.   This case was linked to US-MODERNATX, INC.-MOD-2022-662961, US-MODERNATX, INC.-MOD-2022-662973, US-MODERNATX, INC.-MOD-2022-662974, US-MODERNATX, INC.-MOD-2022-662887, US-MODERNATX, INC.-MOD-2022-662970, US-MODERNATX, INC.-MOD-2022-662991, US-MODERNATX, INC.-MOD-2022-663001, US-MODERNATX, INC.-MOD-2022-663009, US-MODERNATX, INC.-MOD-2022-663012, US-MODERNATX, INC.-MOD-2022-663015, US-MODERNATX, INC.-MOD-2022-663040, US-MODERNATX, INC.-MOD-2022-663041, US-MODERNATX, INC.-MOD-2022-663044, US-MODERNATX, INC.-MOD-2022-663045, US-MODERNATX, INC.-MOD-2022-663047, US-MODERNATX, INC.-MOD-2022-663091, US-MODERNATX, INC.-MOD-2022-663128, US-MODERNATX, INC.-MOD-2022-663137 (E2B Linked Report).; Sender's Comments:  US-MODERNATX, INC.-MOD-2022-662974:Same reporter US-MODERNATX, INC.-MOD-2022-662973:Same reporter US-MODERNATX, INC.-MOD-2022-662961:Same reporter US-MODERNATX, INC.-MOD-2022-662887:Same reporter US-MODERNATX, INC.-MOD-2022-662970:Same reporter US-MODERNATX, INC.-MOD-2022-662991:Same reporter US-MODERNATX, INC.-MOD-2022-663001:Same reporter US-MODERNATX, INC.-MOD-2022-663009:Same reporter US-MODERNATX, INC.-MOD-2022-663012:Same reporter US-MODERNATX, INC.-MOD-2022-663015:Same reporter US-MODERNATX, INC.-MOD-2022-663040:Same reporter US-MODERNATX, INC.-MOD-2022-663041:Same reporter US-MODERNATX, INC.-MOD-2022-663044:Same reporter US-MODERNATX, INC.-MOD-2022-663045:Same reporter US-MODERNATX, INC.-MOD-2022-663047:Same reporter US-MODERNATX, INC.-MOD-2022-663091:Same reporter US-MODERNATX, INC.-MOD-2022-663128:Same reporter US-MODERNATX, INC.-MOD-2022-663137:Same reporter