no adverse event; he administered 1 dose of Moderna COVID-19 Vaccine Bivalent but it leaked out of the syringe and it was only administered an estimate of 0.2 mL.; on 13JUN2023 he administered 1 dose of Moderna COVID-19 Vaccine Bivalent but it leaked out of the syringe and it was only administered an estimate of 0.2 mL.; to administer the vaccine again on the same day (0.5 mL).; This spontaneous case was reported by a pharmacist and describes the occurrence of ACCIDENTAL UNDERDOSE (he administered 1 dose of Moderna COVID-19 Vaccine Bivalent but it leaked out of the syringe and it was only administered an estimate of 0.2 mL.), SYRINGE ISSUE (on 13JUN2023 he administered 1 dose of Moderna COVID-19 Vaccine Bivalent but it leaked out of the syringe and it was only administered an estimate of 0.2 mL.), EXTRA DOSE ADMINISTERED (to administer the vaccine again on the same day (0.5 mL).) and NO ADVERSE EVENT (no adverse event) in an adult female patient who received mRNA-1273 BIVALENT .222 (MODERNA COVID-19 VACCINE, BIVALENT (ORIGINAL AND OMICRON BA.4/BA.5)) for COVID-19 prophylaxis.     It was unknown whether the patient had any relevant medical history/conditions, allergy, concomitant diseases and risk factor.     On 12-Jun-2023, the patient received dose of mRNA-1273 BIVALENT .222 (MODERNA COVID-19 VACCINE, BIVALENT (ORIGINAL AND OMICRON BA.4/BA.5)) (unknown route) .2 milliliter. On 12-Jun-2023, the patient experienced ACCIDENTAL UNDERDOSE (he administered 1 dose of Moderna COVID-19 Vaccine Bivalent but it leaked out of the syringe and it was only administered an estimate of 0.2 mL.), SYRINGE ISSUE (on 13JUN2023 he administered 1 dose of Moderna COVID-19 Vaccine Bivalent but it leaked out of the syringe and it was only administered an estimate of 0.2 mL.) and EXTRA DOSE ADMINISTERED (to administer the vaccine again on the same day (0.5 mL).). On an unknown date, the patient experienced NO ADVERSE EVENT (no adverse event). At the time of the report, ACCIDENTAL UNDERDOSE (he administered 1 dose of Moderna COVID-19 Vaccine Bivalent but it leaked out of the syringe and it was only administered an estimate of 0.2 mL.), SYRINGE ISSUE (on 13JUN2023 he administered 1 dose of Moderna COVID-19 Vaccine Bivalent but it leaked out of the syringe and it was only administered an estimate of 0.2 mL.), EXTRA DOSE ADMINISTERED (to administer the vaccine again on the same day (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 assessments were provided for ACCIDENTAL UNDERDOSE (he administered 1 dose of Moderna COVID-19 Vaccine Bivalent but it leaked out of the syringe and it was only administered an estimate of 0.2 mL.), SYRINGE ISSUE (on 13JUN2023 he administered 1 dose of Moderna COVID-19 Vaccine Bivalent but it leaked out of the syringe and it was only administered an estimate of 0.2 mL.) and EXTRA DOSE ADMINISTERED (to administer the vaccine again on the same day (0.5 mL).).    No concomitant medication was reported. It was unknown whether the patient receive any other vaccines in the 4 weeks prior to COVID-19 vaccine.  The dosage text of the suspect product was reported as unknown.  No adverse events were reported. No treatment medication was reported.