REVACCINATION WITH DIFFERENT COVID-19 VACCINE; CONFIRMED CLINICAL VACCINATION FAILURE; CONFIRMED COVID-19 INFECTION; This spontaneous report received from a patient via (pfizer) concerned a 76 year old female. Initial information was processed along with additional information on 18-OCT-2022. The patient's height, and weight were not reported. The patient's past medical history included: two parathyroids removed, and concurrent conditions included: hypothyroid (after removal of thyroid (cancer)), gastroesophageal reflux disease, and osteopenia. The patient received covid-19 vaccine ad26.cov2.s (Dose number in series 1) (suspension for injection, route of admin not reported, batch number: 1805022 expiry: unknown) dose was not reported, 1 total, administered on 04-MAR-2021 on right arm for covid-19 prophylaxis.  The patient received two doses of non-company suspect vaccine (Spikevax, moderna covid-19 vaccine) elasomeran (Dose number in series 2) (form of admin, route of admin were not reported, batch number: 071 F21A expiry: unknown) dose was not reported, administered on 27-OCT-2021 on right arm and third dose received (Dose number in series 3) (form of admin, route of admin were not reported, batch number: 005M21A expiry: UNKNOWN) dose was not reported, administered on 15-APR-2022 on right arm for covid-19 prophylaxis which was revaccination with different covid-19 vaccine (Dose number in series 3). Age at time of vaccination 74 years old. Concomitant medications included biotin, calcium, calcium carbonate/colecalciferol, fish oil, levothyroxine, omeprazole, and vitamins nos.  On an unspecified date in 2022, the patient had covid-19 infection (Dose number in series 3). The patient received Nirmatrelvir/ritonavir (Paxlovid) (form of admin, route of admin and batch number were not reported, expiry: unknown) dose was not reported, administered from 24-SEP-2022 to 28-SEP-2022 for covid-19 treatment. On 03-OCT-2022 23:00 (5 days after end of paxlovid), the patient experienced return of Covid symptoms like runny nose, post nasal drip, sneezing, extreme congestion, cough, chills, fatigue, shortness of breath only upon exertion, The patient had positive Covid antigen test 7 days after end of Paxlovid (confirmed covid-19 infection (Dose number in series 3) and had confirmed clinical vaccination failure (Dose number in series 1). On 05-OCT-2022, Laboratory data included: COVID-19 antigen test Positive. Treatment medications (dates unspecified) included: ibuprofen, pseudoephedrine hydrochloride, dextromethorphan, and guaifenesin for covid-19. The action taken with covid-19 vaccine ad26.cov2.s and elasomeran was not applicable and with paxlovid treatment discontinued. The patient was recovering 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 product quality complaint 90000255690.; Sender's Comments: V0: 20221030593-covid-19 vaccine ad26.cov2.s-confirmed clinical vaccination failure . The event(s) 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(s) than the drug. Specifically: SPECIAL SITUATIONS. Therefore, this event(s) is considered not related.