COVID-19; Interchange of vaccine products; This spontaneous case was reported by a patient and describes the occurrence of COVID-19 (COVID-19) and INTERCHANGE OF VACCINE PRODUCTS (Interchange of vaccine products) in a 33-year-old female patient who received mRNA-1273 (Moderna COVID-19 Vaccine) (batch no. 088D21A) for COVID-19 vaccination.     Previously administered products included for Product used for unknown indication: J&J vaccine (Dose Number: 1 Batch/Lot No: 042A21A Location of injection: Left arm) on 02-Apr-2021. Past adverse reactions to the above products included No adverse event with J&J vaccine. Concurrent medical conditions included Drug allergy (Unspecified drug.).    On 13-Aug-2021, the patient received second dose of mRNA-1273 (Moderna COVID-19 Vaccine) (unknown route) 1 dosage form. On an unknown date, the patient experienced COVID-19 (COVID-19) and INTERCHANGE OF VACCINE PRODUCTS (Interchange of vaccine products). The patient was treated with NIRMATRELVIR, RITONAVIR (PAXLOVID) from 23-May-2022 to 27-May-2022 for COVID-19 treatment, 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.      DIAGNOSTIC RESULTS (normal ranges are provided in parenthesis if available): On an unknown date, SARS-CoV-2 test: positive (Positive) Positive (first episode).         Patient was not taking other medications/products within 2 weeks of starting COVID-19 treatment. Patient previously received a COVID-19 Vaccine. Concomitant medication information was not provided by the reporter. On 31-May-2022 at 21:00 PM, the patient experienced a rebound COVID infection, 4 days after stopping treatment with Paxlovid. It started with intense congestion and then the rest of the symptoms followed.Device date was reported as 03-Jun-2022. Company Comment: This spontaneous case concerns a 33 year old female patient  initially vaccinated with Covid 19 Vaccine Janssen for 1 dose  , who experienced non-serious , unexpected , AESI of Covid 19 which occurred on an unknown date post vaccination with the dose 2 of mRNA-1273 vaccine. The patient was treated with NIRMATRELVIR, RITONAVIR (PAXLOVID) from 23-May-2022 to 27-May-2022 for COVID-19 treatment, at an unspecified dose and frequency.  However the patient reported that she experienced a rebound COVID infection 4 days after stopping treatment which started with intense congestion and then the rest of the symptoms followed . It was reported that the patient had a SARS-COV-2 test positive on 31-May-2022.  Results  of other laboratories/diagnostic procedures , other treatment information and if any medical consult was done were not reported.  Event of  Interchange of Vaccine products also occurred. Outcome of the event was reported as resolved. The benefit -risk relationship of mRNA -1273 ( Moderna Covid 19 Vaccine) is not affected by this report.; Sender's Comments: This spontaneous case concerns a 33 year old female patient  initially vaccinated with Covid 19 Vaccine Janssen for 1 dose  , who experienced non-serious , unexpected , AESI of Covid 19 which occurred on an unknown date post vaccination with the dose 2 of mRNA-1273 vaccine. The patient was treated with NIRMATRELVIR, RITONAVIR (PAXLOVID) from 23-May-2022 to 27-May-2022 for COVID-19 treatment, at an unspecified dose and frequency.  However the patient reported that she experienced a rebound COVID infection 4 days after stopping treatment which started with intense congestion and then the rest of the symptoms followed . It was reported that the patient had a SARS-COV-2 test positive on 31-May-2022.  Results  of other laboratories/diagnostic procedures , other treatment information and if any medical consult was done were not reported.  Event of  Interchange of Vaccine products also occurred. Outcome of the event was reported as resolved. The benefit -risk relationship of mRNA -1273 ( Moderna Covid 19 Vaccine) is not affected by this report.