Interchange of vaccine products; Rebound sx of Covid-19 (URI sx and positive antigen test; Lack of drug effect; This spontaneous case was reported by an other health care professional and describes the occurrence of COVID-19 (Rebound sx of Covid-19 (URI sx and positive antigen test), DRUG INEFFECTIVE (Lack of drug effect) and INTERCHANGE OF VACCINE PRODUCTS (Interchange of vaccine products) in a 76-year-old male patient who received mRNA-1273 (Moderna COVID-19 Vaccine) for COVID-19 vaccination.    Co-suspect product included non-company product TOZINAMERAN (PFIZER BIONTECH COVID-19 VACCINE) for an unknown indication.    Concurrent medical conditions included Hypertension (Htn), Type 2 diabetes mellitus (DM2) and Allergy.   On 07-Jan-2021, the patient received first dose of mRNA-1273 (Moderna COVID-19 Vaccine) (unknown route) 1 dosage form. On 08-Feb-2021, received second dose of mRNA-1273 (Moderna COVID-19 Vaccine) (unknown route) dosage was changed to 1 dosage form. On 02-Nov-2021, the patient received third dose of TOZINAMERAN (PFIZER BIONTECH COVID-19 VACCINE) (unknown route) 1 dosage form. On 17-May-2022 at 8:00 PM, the patient experienced COVID-19 (Rebound sx of Covid-19 (URI sx and positive antigen test) and DRUG INEFFECTIVE (Lack of drug effect). On an unknown date, the patient experienced INTERCHANGE OF VACCINE PRODUCTS (Interchange of vaccine products). The patient was treated with NIRMATRELVIR, RITONAVIR (PAXLOVID) from 06-May-2022 to 10-May-2022 for COVID-19 treatment, at an unspecified dose and frequency. At the time of the report, COVID-19 (Rebound sx of Covid-19 (URI sx and positive antigen test) was resolving and DRUG INEFFECTIVE (Lack of drug effect) and INTERCHANGE OF VACCINE PRODUCTS (Interchange of vaccine products) outcome was unknown.      DIAGNOSTIC RESULTS (normal ranges are provided in parenthesis if available): On an unknown date, SARS-CoV-2 test: positive (Positive) Positive.     For mRNA-1273 (Moderna COVID-19 Vaccine) (Unknown), the reporter did not provide any causality assessments.   No concomitant medications were reported   It was unknown if the patient took any other medications or products within 2 weeks of starting COVID-19 treatment Device Date was reported as 18-May-2022  Company Comment: This spontaneous case of Interchange of vaccine products and Drug ineffective concerns a 76-year-old male patient, with previous vaccination of Tozinameran and concurrent Hypertension and Type 2 Diabetes mellitus, who experienced the unexpected AESI of COVID-19. The event occurred approximately 14 months after receiving the second dose of mRNA-1273 Vaccine. The patient was treated with NIRMATRELVIR, RITONAVIR (PAXLOVID) for COVID-19, however the patient developed upper respiratory tract infection and positive SARS-CoV-2 antigen test 7 days after completing Paxlovid treatment. The outcome of the event was reported as unknown. The patient's medical history of previous vaccination of Tozinameran, concurrent Hypertension and Type 2 Diabetes mellitus, and Paxlovid treatment remain as confounders for the occurrence of the event. The benefit-risk relationship of mRNA-1273 Vaccine is not affected by this report.; Sender's Comments: This spontaneous case of Interchange of vaccine products and Drug ineffective concerns a 76-year-old male patient, with previous vaccination of Tozinameran and concurrent Hypertension and Type 2 Diabetes mellitus, who experienced the unexpected AESI of COVID-19. The event occurred approximately 14 months after receiving the second dose of mRNA-1273 Vaccine. The patient was treated with NIRMATRELVIR, RITONAVIR (PAXLOVID) for COVID-19, however the patient developed upper respiratory tract infection and positive SARS-CoV-2 antigen test 7 days after completing Paxlovid treatment. The outcome of the event was reported as unknown. The patient's medical history of previous vaccination of Tozinameran, concurrent Hypertension and Type 2 Diabetes mellitus, and Paxlovid treatment remain as confounders for the occurrence of the event. The benefit-risk relationship of mRNA-1273 Vaccine is not affected by this report.