No adverse event; Received 0.25 ml of bivalent dose; This spontaneous case was reported by a nurse and describes the occurrence of ACCIDENTAL UNDERDOSE (Received 0.25 ml of bivalent dose) and NO ADVERSE EVENT (No adverse event) in a 71-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). 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) 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).    No concomitant medications were provided. 19 patients who received the half doses on 15Sep2022, 22Sep2022, 29Sep2022, and 06Oct2022. This case was created for one of the 19 patients. No treatment medications were reported.   This case was linked to US-MODERNATX, INC.-MOD-2022-662961, US-MODERNATX, INC.-MOD-2022-662973, US-MODERNATX, INC.-MOD-2022-662887, US-MODERNATX, INC.-MOD-2022-662970, US-MODERNATX, INC.-MOD-2022-662974, 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, US-MODERNATX, INC.-MOD-2022-663147, US-MODERNATX, INC.-MOD-2022-662974 (E2B Linked Report).; Sender's Comments:  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-2022-662974: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 US-MODERNATX, INC.-MOD-2022-663147:Same reporter US-MODERNATX, INC.-MOD-2022-662974:Same reporter