INTENSIVE CARE; ENDOTRACHEAL INTUBATION; PYREXIA; PALPITATIONS; FATIGUE; CONFIRMED CLINICAL VACCINATION FAILURE; COVID-19; SARS-COV-2 TEST POSITIVE; MYASTHENIA GRAVIS; BILEVEL POSITIVE AIRWAY PRESSURE; CONDITION AGGRAVATED; DYSPNOEA; COUGH; ASTHENIA; This spontaneous report received from a health care professional via the Regulatory Authority VAERS (Vaccine Adverse Event Reporting System) (ID: 1641207) concerned a 55 year old female, unspecified race and ethnicity. The patient's height, and weight were not reported. The patient's past medical history included: former smoker, and concurrent conditions included: asthma, cad, hyperlipidemia, hypertension, and myasthenia gravis, and other pre-existing medical conditions included: No known allergy. The patient received covid-19 vaccine ad26.cov2.s (suspension for injection, route of administration was not reported, batch number: 1805025 expiry: unknown) dose was not reported, frequency 1 total, administered on 21-MAR-2021 for prophylactic vaccination. Concomitant medications included cetirizine, ferrous sulfate, and salbutamol. On 14-JUL-2021, the patient experienced dry cough (cough), progressive short of breath (dyspnoea), and generalized weakness (asthenia) and myasthenia gravis flare up (condition aggravated). On 18-JUL-2021, the patient experienced myasthenia gravis, covid-19, fatigue, and BiPAP (bilevel positive airway pressure). On 18-JUL-2021, Laboratory data included: SARS-CoV-2 PCR test (NR: not provided) Positive (confirmed clinical vaccination failure). On 23-JUL-2021, the patient experienced palpitations and pyrexia. On 30-JUL-2021, the patient was intubated (endotracheal intubation) due to increased fatigue while on BiPAP. On 15-AUG-2021, the patient was transferred to hospital intensive care unit and remains intubated, not tolerating weaning of sedation. The action taken with covid-19 vaccine ad26.cov2.s was not applicable. The patient had not recovered from myasthenia gravis, condition aggravated, dyspnoea, cough, asthenia, covid-19, sars-cov-2 test positive, palpitations, fatigue, bilevel positive airway pressure, endotracheal intubation, intensive care and recovered from pyrexia on 22-AUG-2021, and the outcome of confirmed clinical vaccination failure was not reported. This report was serious (Hospitalization Caused / Prolonged). This case is associated with complaint number 90000193180. The suspected product quality complaint has been confirmed to be not voided, the reported allegation could not be confirmed. A manufacturing related root cause could not be identified based on the product quality complaint evaluation and investigation performed.  Additional information received from Complaint Vigilance department on 21-OCT-2021. The following information was updated and incorporated into the case narrative: quality complaint investigation result.; Sender's Comments: V1: This follow up adds- quality complaint investigation result. This new information does not change prior causality assessment. 20210920735- Covid-19 vaccine ad26.cov2.s- Confirmed clinical vaccination failure. This event(s) is considered not related. 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 20210920735- Covid-19 vaccine ad26.cov2.s- Myasthenia gravis, condition aggravated, dyspnoea, cough, asthenia, covid-19, sars-cov-2 test positive, palpitations, fatigue, pyrexia, bilevel positive airway pressure, endotracheal intubation, intensive care. This event(s) is considered not related. 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: MEDICAL HISTORY