COVID rebound on day 13 from positive test (after taking Paxlovid on days 1-5); Lack of efficacy; This spontaneous case was reported by a consumer and describes the occurrence of COVID-19 (COVID rebound on day 13 from positive test (after taking Paxlovid on days 1-5)) and DRUG INEFFECTIVE (Lack of efficacy) in a 43-year-old female patient who received mRNA-1273 (Moderna COVID-19 Vaccine) (batch nos. 048F21A, 028A21A and 031M20A) for COVID-19 vaccination.     The patient had no drug allergy. The patient had previously received a COVID-19 vaccine.  Concurrent medical conditions included Immunocompromised (Unexplained immunocompromisation). Concomitant products included TOZINAMERAN (PFIZER BIONTECH COVID-19 VACCINE) for COVID-19 vaccination, CETIRIZINE HYDROCHLORIDE (ZYRTEC [CETIRIZINE HYDROCHLORIDE]), FLUTICASONE PROPIONATE, SALMETEROL XINAFOATE (WIXELA INHUB) from 30-Apr-2022 to 11-May-2022, VITAMIN D NOS, VITAMIN B NOS, AZELASTINE HYDROCHLORIDE, FLUTICASONE PROPIONATE (DYMISTA) and FAMOTIDINE for an unknown indication.   On 27-Feb-2021 at 3:00 PM, the patient received first dose of mRNA-1273 (Moderna COVID-19 Vaccine) (unknown route) 1 dosage form. On 27-Mar-2021 at 3:00 PM, received second dose of mRNA-1273 (Moderna COVID-19 Vaccine) (unknown route) dosage was changed to 1 dosage form. On 18-Sep-2021 at 10:00 AM, received third dose of mRNA-1273 (Moderna COVID-19 Vaccine) (unknown route) dosage was changed to 1 dosage form. On 13-May-2022, the patient experienced COVID-19 (COVID rebound on day 13 from positive test (after taking Paxlovid on days 1-5)) and DRUG INEFFECTIVE (Lack of efficacy). The patient was treated with NIRMATRELVIR, RITONAVIR (PAXLOVID) from 01-May-2022 to 05-May-2022 for COVID-19 treatment, at an unspecified dose and frequency. At the time of the report, COVID-19 (COVID rebound on day 13 from positive test (after taking Paxlovid on days 1-5)) and DRUG INEFFECTIVE (Lack of efficacy) outcome was unknown.      DIAGNOSTIC RESULTS (normal ranges are provided in parenthesis if available): On 01-May-2022, SARS-CoV-2 test: positive (Positive) Positive. On 13-May-2022, SARS-CoV-2 test: positive (Positive) Positive.         The patient was taking other medications/products within 2 weeks of starting COVID-19 treatment.  On 13-May-2022, at 05:00 hours, the patient had rebound of COVID-19 infection on day 13 from positive test.  CC: This spontaneous case concerns a 43-year-old female patient, with a relevant history of unexplained immunocompromised state, who experienced the unexpected, non-serious Adverse Event of Special Interest of COVID-19, which occurred 7 months, 25 days after mRNA-1273 vaccine administration as third dose and 44 days after the administration of Pfizer/BioNtech COIVD-19 vaccine as the fourth dose. Additionally, an event drug ineffective was also noted. Patient reported testing positive for COVID-19 and was treated with Paxlovid, however, had rebound COVID-19 about 13 days after taking Paxlovid. The outcome of the events was reported as unknown. The patient had received initial two doses of mRNA-1273 vaccine as primary series in accordance to recommended schedule approximately 1 year and 3 months ago. The ongoing COVID-19 pandemic and underlying history of unexplained immunocompromised state could be risk factors for the events. The benefit-risk relationship of mRNA-1273 vaccine is not affected by this report.  The device date was reported as 14-May-2022.; Sender's Comments: This spontaneous case concerns a 43-year-old female patient, with a relevant history of unexplained immunocompromised state, who experienced the unexpected, non-serious Adverse Event of Special Interest of COVID-19, which occurred 7 months, 25 days after mRNA-1273 vaccine administration as third dose and 44 days after the administration of Pfizer/BioNtech COIVD-19 vaccine as the fourth dose. Additionally, an event drug ineffective was also noted. Patient reported testing positive for COVID-19 and was treated with Paxlovid, however, had rebound COVID-19 about 13 days after taking Paxlovid. The outcome of the events was reported as unknown. The patient had received initial two doses of mRNA-1273 vaccine as primary series in accordance to recommended schedule approximately 1 year and 3 months ago. The ongoing COVID-19 pandemic and underlying history of unexplained immunocompromised state could be risk factors for the events. The benefit-risk relationship of mRNA-1273 vaccine is not affected by this report.