Paxlovid Rebound; RECEIVED PFIZER BIONTECH COVID-19 VACCINE AS THIRD DOSE; This spontaneous case was reported by a consumer and describes the occurrence of COVID-19 (Paxlovid Rebound) and INTERCHANGE OF VACCINE PRODUCTS (RECEIVED PFIZER BIONTECH COVID-19 VACCINE AS THIRD DOSE) in a 73-year-old female patient who received mRNA-1273 (Moderna COVID-19 Vaccine) (batch nos. 007M20A and 011A21A) for COVID-19 vaccination.    Co-suspect product included non-company product NIRMATRELVIR, RITONAVIR (PAXLOVID) for COVID-19 treatment.    Concurrent medical conditions included Hypothyroidism and Sulfonamide allergy. Concomitant products included TOZINAMERAN (PFIZER BIONTECH COVID-19 VACCINE), LEVOTHYROXINE, VITAMIN C [ASCORBIC ACID], VITAMIN D3, VITAMIN B12 [VITAMIN B12 NOS], ZINC, MAGNESIUM, CALCIUM CITRATE, SELENIUM and PROBIOTICS NOS for an unknown indication.   On 20-Feb-2021, the patient received second dose of mRNA-1273 (Moderna COVID-19 Vaccine) (unknown route) 1 dosage form. On 20-Mar-2021, received second dose of mRNA-1273 (Moderna COVID-19 Vaccine) (unknown route) dosage was changed to 1 dosage form. On 04-May-2022, the patient started NIRMATRELVIR, RITONAVIR (PAXLOVID) (unknown route) at an unspecified dose. On 08-Nov-2021, the patient experienced INTERCHANGE OF VACCINE PRODUCTS (RECEIVED PFIZER BIONTECH COVID-19 VACCINE AS THIRD DOSE). On an unknown date, the patient experienced COVID-19 (Paxlovid Rebound). At the time of the report, COVID-19 (Paxlovid Rebound) was resolving and INTERCHANGE OF VACCINE PRODUCTS (RECEIVED PFIZER BIONTECH COVID-19 VACCINE AS THIRD DOSE) outcome was unknown.            On 15-May-2022, patient had Paxlovid Rebound. Other concomitant medication was reported as Youtheory (Collagen + Biotin) 6000mg and Kirkland (vitamin C 1000). Patient was on other medications/products within 2 weeks of starting COVID-19 treatment.  Company Comment: This spontaneous case concerns a 73-year-old, female patient with no relevant medical history who experienced the unexpected, non-serious adverse event of special interest of COVID-19 which occurred on unknown date after receiving the second dose of mRNA-1273 vaccine. The second dose was administered 28 days after the first dose of mRNA-1273 vaccine which is within the recommended dosing interval. Interchange of vaccine products is noted in this case as patient received Pfizer Biontech COVID-19 vaccine as third dose of COVID-19 immunization. It was reported that patient was treated with Nirmatrelvir, Ritonavir (Paxlovid) for 6 days for COVID-19 but developed recurrence of COVID-19 after treatment completion. The clinical course and details of COVID-19 test were not reported. The benefit-risk relationship of mRNA-1273 is not affected by this report.; Sender's Comments: This spontaneous case concerns a 73-year-old, female patient with no relevant medical history who experienced the unexpected, non-serious adverse event of special interest of COVID-19 which occurred on unknown date after receiving the second dose of mRNA-1273 vaccine. The second dose was administered 28 days after the first dose of mRNA-1273 vaccine which is within the recommended dosing interval. Interchange of vaccine products is noted in this case as patient received Pfizer Biontech COVID-19 vaccine as third dose of COVID-19 immunization. It was reported that patient was treated with Nirmatrelvir, Ritonavir (Paxlovid) for 6 days for COVID-19 but developed recurrence of COVID-19 after treatment completion. The clinical course and details of COVID-19 test were not reported. The benefit-risk relationship of mRNA-1273 is not affected by this report.