CONFIRMED IMMUNOLOGICAL VACCINATION FAILURE; This spontaneous report received from a patient concerned a 50 year old male. Initial information was processed with the additional information received on 14-JAN-2022. The patient's height, and weight were not reported. The patient's past medical history included: MRSA infection, and septic. Four years ago in 2017, patient was admitted to the hospital due to methicillin-resistant staphylococcus aureus infection (MRSA infection) in the torso and legs and he was injected with 4 bags of vancomycin. He was going septic. Patient's concurrent conditions included: non smoker, allergic to bactrim, acquired immunodeficiency syndrome (AIDS). The patient was diagnosed with AIDS in March 1999. Patient T cells were 100. He was taking his treatment for AIDS regularly and the virus had became undetected with T Cells of 1500. The patient had no exposure to SARS-COV2- virus, no positive symptoms of COVID-19, and no positive COVID-19 test/diagnosis prior to vaccination. The patient was not hospitalized. The patient had no any issue with vaccine or during administration of vaccine (e.g., syringe leak, needle disconnect). On 28-SEP-2020, Laboratory data included: SARS-CoV-2 RNA (NR: not provided) Not Detected. The patient previously received covid-19 vaccine ad26. cov2.s (Janssen, dose number in series 1) (suspension for injection, route of admin not reported, batch number: 042A21A, expiry: unknown) dose was not reported, 1 total, administered on 01-APR-2021 to left arm for prophylactic vaccination.  On 29-JUL-2021, patient's antibodies test came back negative and patient experienced confirmed immunological vaccine failure. Laboratory data included: Antibody test (NR: not provided) Negative. With all the past experience in mind, patient was concerned of having undetectable antibodies. He wanted to wait for the Janssen vaccine booster. His doctor recommended to take Moderna or Pfizer vaccine in order to develop antibodies (Dose number in series1). The patient received covid-19 vaccine ad26.cov2.s (dose number in series 2) (suspension for injection, route of admin, and batch number were not reported) dose was not reported, 1 total, administered on 24-OCT-2021 for prophylactic vaccination. The batch number was not reported and has been requested. Concomitant medications included bictegravir sodium/emtricitabine/tenofovir alafenamide fumarate and valaciclovir for hiv-1 infection.  On 04-JAN-2022, the patient SARS-CoV-2 IgG antibody test and SARS-CoV-2 IgM antibody test came negative and hence patient experienced confirmed immunological vaccine failure (Dose number in series 2). The action taken with covid-19 vaccine ad26.cov2.s was not applicable. The outcome of confirmed immunological vaccination failure was not reported. This report was serious (Other Medically Important Condition). This report was associated with product quality complaint: 90000211940 This case, involving the same patient is linked to 20211022439 (Dose number in series 1).; Sender's Comments: V0: 20220124525-Covid-19 vaccine ad26.cov2.s-confirmed immunological vaccine failure . This event is considered not related. 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 than the drug. Specifically: SPECIAL SITUATIONS