Patient took Paxlovid for treatment of COVID-19 and Rebound symptoms returned 4 days after completing 5 days of Paxlovid; This spontaneous case was reported by a consumer and describes the occurrence of COVID-19 (Patient took Paxlovid for treatment of COVID-19 and Rebound symptoms returned 4 days after completing 5 days of Paxlovid) in a 66-year-old female patient who received mRNA-1273 (Moderna COVID-19 Vaccine) (batch nos. 007M20A, 048C21A, 029A21A and 007M20A) for COVID-19 vaccination.     Concurrent medical conditions included Breast cancer and Drug allergy (unknown drug). Concomitant products included ANASTROZOLE (ARIMIDEX) from 20-Oct-2021 to an unknown date and AMLODIPINE from 04-Jul-2019 to an unknown date for an unknown indication.   On 05-Feb-2021, the patient received first dose of mRNA-1273 (Moderna COVID-19 Vaccine) (unknown route) 1 dosage form. On 05-Mar-2021, received second dose of mRNA-1273 (Moderna COVID-19 Vaccine) (unknown route) dosage was changed to 1 dosage form. On 26-Oct-2021, received third dose of mRNA-1273 (Moderna COVID-19 Vaccine) (unknown route) dosage was changed to 1 dosage form. On 08-Apr-2022, received fourth dose of mRNA-1273 (Moderna COVID-19 Vaccine) (unknown route) dosage was changed to 1 dosage form. On an unknown date, the patient experienced COVID-19 (Patient took Paxlovid for treatment of COVID-19 and Rebound symptoms returned 4 days after completing 5 days of Paxlovid). The patient was treated with NIRMATRELVIR, RITONAVIR (PAXLOVID) from 09-May-2022 to 14-May-2022 for COVID-19 treatment, at an unspecified dose and frequency. At the time of the report, COVID-19 (Patient took Paxlovid for treatment of COVID-19 and Rebound symptoms returned 4 days after completing 5 days of Paxlovid) was resolving.            Patient's race was reported as Caucasian. The patient received Paxlovid for treatment of COVID-19. On 18-May-2022, 4 days after completing 5 days treatment with Paxlovid, the patient experienced rebound symptoms.  Company Comment: This spontaneous case concerns a 66-year-old female patient, with concurrent breast cancer, who experienced the unexpected non-serious adverse event of special interest COVID-19 that occurred on an unknown date after receiving the fourth dose of mRNA-1273 vaccine. Patient experienced rebound of COVID-19 symptoms 4 days after completion of a 5-day course of NIRMATRELVIR, RITONAVIR (Paxlovid) for COVID-19 treatment. No COVID-19 test was reported. Outcome of the event was reported as resolved. Patient previously received 3 doses of mRNA-1273 vaccines consisting of a 2-dose primary series given 28 days apart, and a third dose given 5 months and 13 days prior to current mRNA-1273 vaccine. The concurrent breast cancer could be considered as a predisposing factor to COVID-19. The benefit-risk relationship of mRNA-1273 is not affected by this report.; Sender's Comments: This spontaneous case concerns a 66-year-old female patient, with concurrent breast cancer, who experienced the unexpected non-serious adverse event of special interest COVID-19 that occurred on an unknown date after receiving the fourth dose of mRNA-1273 vaccine. Patient experienced rebound of COVID-19 symptoms 4 days after completion of a 5-day course of NIRMATRELVIR, RITONAVIR (Paxlovid) for COVID-19 treatment. No COVID-19 test was reported. Outcome of the event was reported as resolved. Patient previously received 3 doses of mRNA-1273 vaccines consisting of a 2-dose primary series given 28 days apart, and a third dose given 5 months and 13 days prior to current mRNA-1273 vaccine. The concurrent breast cancer could be considered as a predisposing factor to COVID-19. The benefit-risk relationship of mRNA-1273 is not affected by this report.