CONFIRMED CLINICAL VACCINATION FAILURE; CONFIRMED COVID-19 INFECTION; REVACCINATION WITH DIFFERENT COVID-19 VACCINE; This spontaneous report received from other manufacturer Pfizer concerned a patient of unspecified age, sex, race and ethnicity. Initial information was processed with the additional information received on 14-DEC-2022. The patient's height, and weight were not reported. The patient's concurrent conditions included: MS (Multiple sclerosis), breast cancer, sulfa allergy, and drug allergy (Copaxone (Glatiramer acetate)). The patient received covid-19 vaccine ad26.cov2.s (Dose number in series 1) (suspension for injection, route of admin, and batch number were not reported, expiry: unknown) dose, start therapy date were not reported, 1 total administered in left arm for covid-19 prophylaxis. The batch number was not reported. The Company is unable to perform follow-up to request batch/lot numbers. The patient received non-company suspect vaccine tozinameran (Pfizer Biontech covid-19 vaccine) (Dose number in series 2) (form of admin, route of admin, and batch number were not reported, expiry: Unknown) dose, start therapy date were not reported administered in left arm for covid-19 prophylaxis. It was unknown whether patient had any adverse events following vaccination with tozinameran (Pfizer Biontech covid-19 vaccine) (Dose number in series 2). The patient received non-company suspect vaccine elasomeran (Moderna covid-19 vaccine) (Dose number in series 3) (form of admin, route of admin, and batch number were not reported, expiry: unknown) dose was not reported administered on 01-JUN-2022 in left arm for covid-19 prophylaxis which was revaccination with different covid-19 vaccine (Dose number in series 3). No concomitant medications were reported. On an unspecified date in NOV-2022, the patient had covid-19 infection (Dose number in series 3) for which patient received non-company suspect drug Paxlovid (form of admin, route of admin, and batch number were not reported, expiry: unknown) dose was not reported, from 22-NOV-2022 to 26-NOV-2022 (5 days treatment). The patient also received treatment of antibiotics (unspecified) and nasal spray from 21-NOV-2022 to 26-NOV-2022. On 29-NOV-2022 06:00, the patient developed rebound covid (Dose number in series 3). On 02-DEC-2022 (six days after treatment with Paxlovid), the patient tested positive for covid-19 which was confirmed covid-19 infection (Dose number in series 3) and confirmed clinical vaccination failure (Dose number in series 1). On an unspecified date in 2022, Laboratory data included: COVID-19 virus test Negative. The action taken with covid-19 vaccine ad26.cov2.s, tozinameran and elasomeran was not applicable. The outcome of the confirmed covid-19 infection, confirmed clinical vaccination failure and revaccination with different covid-19 vaccine was not reported. This report was serious (Other Medically Important Condition). This report was associated with a product quality complaint: 90000263179.; Sender's Comments: V0- 20221227910- Confirmed clinical vaccination failure. The event has an unknown/unclear temporal relationship, is unlabeled, and has unknown scientific plausibility. There are other factors more likely to be associated with the event. Specifically: SPECIAL SITUATIONS. Therefore, this event is considered inconsistent with vaccine administration.