Interchange of vaccine products; COVID 19; This spontaneous case was reported by a consumer and describes the occurrence of COVID-19 (COVID 19) and INTERCHANGE OF VACCINE PRODUCTS (Interchange of vaccine products) in a  patient of an unknown age and gender who received mRNA-1273 (Moderna COVID-19 Vaccine) for COVID-19 vaccination.     Previously administered products included for Product used for unknown indication: Pfizer / BioNTech (Dose Number: 1 Batch/Lot No: Unknown.Misplaced/discarded) on 04-Jan-2021 and Pfizer / BioNTech (Dose Number: 2 Batch/Lot No: Unknown.Misplaced/discarded) on 23-Jan-2021. Past adverse reactions to the above products included No adverse reaction with Pfizer / BioNTech and Pfizer / BioNTech. Concurrent medical conditions included Allergy.   On 24-Jul-2021, the patient received third dose of mRNA-1273 (Moderna COVID-19 Vaccine) (unknown route) 1 dosage form. On 07-Jan-2022, received fourth dose of mRNA-1273 (Moderna COVID-19 Vaccine) (unknown route) dosage was changed to 1 dosage form. On 11-May-2022, the patient experienced COVID-19 (COVID 19). On an unknown date, the patient experienced INTERCHANGE OF VACCINE PRODUCTS (Interchange of vaccine products). The patient was treated with NIRMATRELVIR, RITONAVIR (PAXLOVID) from 02-May-2022 to 06-May-2022 for COVID-19 prophylaxis, at an unspecified dose and frequency. At the time of the report, COVID-19 (COVID 19) had resolved and INTERCHANGE OF VACCINE PRODUCTS (Interchange of vaccine products) outcome was unknown. Not Provided    DIAGNOSTIC RESULTS (normal ranges are provided in parenthesis if available): On an unknown date, SARS-CoV-2 test: negative (Negative) The antibody test after Paxlovid course was negative and positive (Positive) symptoms returned, the Ag became positive again..         No concomitant medications were reported.  It was reported patient was not taking any other medications/products within 2 weeks of starting COVID-19 treatment. The original course was very mild and return symptoms were also mild.  The antibody test after Paxlovid course was negative, but when symptoms returned, the Ag became positive again. Device date was reported as 18May2022.  Company comment: This spontaneous case concerns a patient of unknown age and gender with no relevant medical history who experienced the unexpected non serious AESI of COVID 19 which occurred unknown days after the administration of fourth dose of mRNA-1273 vaccine in COVID 19 vaccination series. Initial Covid symptoms were mild. Patient received NIRMATRELVIR, RITONAVIR (Paxlovid) for 5 days as treatment for COVID 19 from 02-May to 06-May. Patient tested negative for COVID 19. 5 days later the symptoms returned, and patient again tested positive for COVID 19 on 11-May. Patient received 2 doses of comirnaty COVID 19 vaccine and 1 dose of mRNA-1273 vaccine 12, 11 and 5 months respectively prior to the last dose (interchange of vaccine products noted). The benefit-risk relationship of mRNA-1273 is not affected by this report.   Reporter did not allow further contact; Sender's Comments: This spontaneous case concerns a patient of unknown age and gender with no relevant medical history who experienced the unexpected non serious AESI of COVID 19 which occurred unknown days after the administration of fourth dose of mRNA-1273 vaccine in COVID 19 vaccination series. Initial Covid symptoms were mild. Patient received NIRMATRELVIR, RITONAVIR (Paxlovid) for 5 days as treatment for COVID 19 from 02-May to 06-May. Patient tested negative for COVID 19. 5 days later the symptoms returned, and patient again tested positive for COVID 19 on 11-May. Patient received 2 doses of comirnaty COVID 19 vaccine and 1 dose of mRNA-1273 vaccine 12, 11 and 5 months respectively prior to the last dose (interchange of vaccine products noted). The benefit-risk relationship of mRNA-1273 is not affected by this report.