CONFIRMED CLINICAL VACCINATION FAILURE; CONFIRMED COVID-19 INFECTION; REVACCINATION WITH DIFFERENT COVID-19 VACCINE; This spontaneous report received from a patient via other manufacturer company (Pfizer) concerned a patient of unspecified age, sex, race and ethnic origin. Initial information was processed along with the additional information received on 18-OCT-2023.  The patient's height, and weight were not reported. The patient's concurrent conditions included: allergy, osteoporosis, and glaucoma. The patient received first dose with covid-19 vaccine ad26.cov2.s (Dose number in series 1), (suspension for injection, route of admin not reported, batch number: 1805018, expiry: unknown) dose was not reported, 1 in total, administered to left arm on 14-MAR-2021 for covid-19 prophylaxis. Concomitant medications included alendronate sodium, and latanoprost.  The patient additionally received second dose of Non-company suspect vaccine Moderna covid-19 vaccine, (elasomeran), (Dose number in series 2), (batch number: 041C21A, expiry: unknown, form of admin, route of admin were not reported) dose was not reported, administered to right arm on 28-OCT-2021 for covid-19 prophylaxis.  It was unknown whether patient had any adverse events following vaccination with second dose of Non-company suspect vaccine Moderna covid-19 vaccine, (elasomeran) (Dose number in series 2). The patient also received third dose with Non-company suspect vaccine Moderna covid-19 vaccine, (elasomeran), (Dose number in series 3), (batch number: 017B22A, expiry: unknown, form of admin, route of admin were not reported) dose was not reported, administered to right arm on 15-JUL-2022 for covid-19 prophylaxis which was revaccination with different covid-19 vaccine (Dose number in series 3).  On an unspecified date in 2023, the patient experienced confirmed covid-19 infection (Dose number in series 3) which lead to confirmed clinical vaccination failure (Dose number in series 1).  The patient started taking treatment with nirmatrelvir/ritonavir (batch number: GH2642, expiry: unknown, form of admin, route of admin were not reported) dose and frequency were not reported from 02-OCT-2023 to 06-OCT-2023 for confirmed covid-19 infection. The patient was taking other medications/products within 2 weeks of starting COVID-19 treatment. It was reported that, when the patient begun taking Paxlovid, COVID-19 symptoms improved right away. By the week of 08-OCT-2023, the patient was feeling great and COVID-19 test on 10-OCT-2023 barely registered positive. On 10-OCT-2023, Laboratory data included: COVID-19 virus test Positive. On 12-OCT-2023, the patient woke up with a very stuffy nose, sneezing and exhausted though no fever. After napping that afternoon, the patient took another test that was clearly strongly positive. On 12-OCT-2023, Laboratory data included: COVID-19 virus test Positive. The patient apparently had a COVID-19 rebound infection (Dose number in series 3). The action taken with covid-19 vaccine ad26.cov2.s, elasomeran (Dose number in series 2), and elasomeran (Dose number in series 3) was not applicable. The patient had not recovered from confirmed covid-19 infection, and the outcome of 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: 90000300682.; Sender's Comments: V0: 20231042898-confirmed clinical vaccination failure. The event has a compatible/suggestive 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.