Moderna vaccine expired on 20-May-2022 and was stored in refrigerator on 07-Jun-2022; No adverse event; Patient received booster dose of expired Moderna COVID-19 vaccine; This spontaneous case was reported by a medical assistant and describes the occurrence of EXPIRED PRODUCT ADMINISTERED (Patient received booster dose of expired Moderna COVID-19 vaccine), PRODUCT STORAGE ERROR (Moderna vaccine expired on 20-May-2022 and was stored in refrigerator on 07-Jun-2022) and NO ADVERSE EVENT (No adverse event) in a 73-year-old patient of an unknown gender who received mRNA-1273 (Moderna COVID-19 Vaccine) (batch no. 033K21-2A) for COVID-19 vaccination.     It was unknown if the patient had ever been diagnosed or tested positive for COVID-19. Chronic and acute illness at the time of vaccination and one month prior was unknown. Allergies to medication, food and other products were not applicable. Other vaccines given within 1 month prior to Moderna COVID-19 vaccine was unknown.    On 12-Feb-2021, the patient received first dose of mRNA-1273 (Moderna COVID-19 Vaccine) (unknown route) 1 dosage form. On 12-Mar-2021, received second dose of mRNA-1273 (Moderna COVID-19 Vaccine) (unknown route) dosage was changed to 1 dosage form. On 04-Jan-2022, received third dose of mRNA-1273 (Moderna COVID-19 Vaccine) (unknown route) dosage was changed to 1 dosage form. On 08-Jun-2022, received fourth dose of mRNA-1273 (Moderna COVID-19 Vaccine) (unknown route) dosage was changed to 1 dosage form. On 08-Jun-2022,  after starting mRNA-1273 (Moderna COVID-19 Vaccine), the patient experienced EXPIRED PRODUCT ADMINISTERED (Patient received booster dose of expired Moderna COVID-19 vaccine). On an unknown date, the patient experienced PRODUCT STORAGE ERROR (Moderna vaccine expired on 20-May-2022 and was stored in refrigerator on 07-Jun-2022) and NO ADVERSE EVENT (No adverse event). At the time of the report, EXPIRED PRODUCT ADMINISTERED (Patient received booster dose of expired Moderna COVID-19 vaccine), PRODUCT STORAGE ERROR (Moderna vaccine expired on 20-May-2022 and was stored in refrigerator on 07-Jun-2022) and NO ADVERSE EVENT (No adverse event) outcome was unknown.        For mRNA-1273 (Moderna COVID-19 Vaccine) (Unknown), the reporter considered NO ADVERSE EVENT (No adverse event) to be not related. No further causality assessments were provided for EXPIRED PRODUCT ADMINISTERED (Patient received booster dose of expired Moderna COVID-19 vaccine) and PRODUCT STORAGE ERROR (Moderna vaccine expired on 20-May-2022 and was stored in refrigerator on 07-Jun-2022).    No concomitant medications were reported. Moderna booster doses were given to 27 patients 19 days after expiration date of 20-May-2022. On 07-Jun-2022, vial was initially stored in the refrigerator. Vial did not undergo any temperature excursions. No adverse event was reported. It was unknown if patient had experienced similar event in the past or if the event caused the patient to seek medical care. No treatment medication was reported.   Most recent FOLLOW-UP information incorporated above includes: On 01-Sep-2022: Follow up received contains significant information: added new reporter, patient demographic details, suspect vaccine details, event details, narrative were updated. On 01-Sep-2022: Live follow up: updated secondary reporter contact details, added dose details of suspect product, updated expiry date, updated narrative. On 02-Sep-2022: Live follow up received contains non significant information.