No adverse event; 17 patients may have received a Moderna bivalent booster dose of 0.25ml instead of 0.5ml; This spontaneous case was reported by a physician and describes the occurrence of UNDERDOSE (17 patients may have received a Moderna bivalent booster dose of 0.25ml instead of 0.5ml) and NO ADVERSE EVENT (No adverse event) in a 24-year-old female patient who received mRNA-1273 BIVALENT .222 (MODERNA COVID-19 VACCINE, BIVALENT (ORIGINAL AND OMICRON BA.4/BA.5)) (batch no. 024422A) for COVID-19 prophylaxis.     The patient had no acute illnesses at the time of vaccination and up to one month before and no allergies to medications, food, and other products. The patient had never been diagnosed with or tested positive for COVID-19.  Concomitant products included INFLUENZA VACCINE INACT SPLIT 3V (FLUARIX), VITAMIN D3 from 01-Nov-2021 to 12-Mar-2022, MAGNESIUM from 01-Nov-2021 to an unknown date, FIBRE, DIETARY (METAMUCIL FIBER GUMMIES) and INFLUENZA VACCINE INACT SPLIT 3V (FLULAVAL) for an unknown indication.    On 03-Dec-2022 at 1:14 PM, the patient received fourth dose of mRNA-1273 BIVALENT .222 (MODERNA COVID-19 VACCINE, BIVALENT (ORIGINAL AND OMICRON BA.4/BA.5)) (Intramuscular) .25 milliliter. On 03-Dec-2022 at 1:14 PM, the patient experienced UNDERDOSE (17 patients may have received a Moderna bivalent booster dose of 0.25ml instead of 0.5ml). On an unknown date, the patient experienced NO ADVERSE EVENT (No adverse event). At the time of the report, UNDERDOSE (17 patients may have received a Moderna bivalent booster dose of 0.25ml instead of 0.5ml) 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)) (Intramuscular), the reporter considered NO ADVERSE EVENT (No adverse event) to be not related. No further causality assessment was provided for UNDERDOSE (17 patients may have received a Moderna bivalent booster dose of 0.25ml instead of 0.5ml).    This case contains information for the 4th of 17 patients described by the reporter.  Patient received Fluarix/Flulaval vaccine on same date of vaccination.  Patient was taking medication of Metamucil fiber singles (3.4 gram) which was mixed as 1 pack in 8 oz of water and taken upto 3 times a daily (1-3 daily) (ongoing). Patient was taking 1 dose of magnesium before bedtime as needed.  On 22-Jul-2021, the patient received first dose of 0.5 ml of Moderna COVID-19 vaccine.  On 18-Aug-2021, the patient received second dose of 0.5 ml of Moderna COVID-19 vaccine.  On 25-Feb-2022., the patient received third dose of 0.5 ml of Moderna COVID-19 vaccine via intramuscular route of administration in the left deltoid (lot no. 083J21A).  The patient was administered with a wrong fourth dose and no other adverse event was reported.  No treatment information was provided.   This case was linked to US-MODERNATX, INC.-MOD-2023-707980 (Linked Report).   Most recent FOLLOW-UP information incorporated above includes: On 07-Jul-2023: Follow up received include patient details updated, suspect Moderna dose details updated, Concomitant medications added, event onset updated, Narrative updated.; Sender's Comments:  US-MODERNATX, INC.-MOD-2023-707980:master case