COVID; Lack of drug effect; This spontaneous case was reported by a consumer and describes the occurrence of COVID-19 (COVID) in a 65-year-old female patient who received mRNA-1273 (Moderna COVID-19 Vaccine) (batch nos. 002A21A and 029L20A) for COVID-19 vaccination. The occurrence of additional non-serious events is detailed below.     Previously administered products included for Product used for unknown indication: Rituxan. Concurrent medical conditions included Rheumatoid arthritis since October 2020.   On 03-Feb-2021, the patient received first dose of mRNA-1273 (Moderna COVID-19 Vaccine) (unknown route) 1 dosage form. On 03-Mar-2021, received second dose of mRNA-1273 (Moderna COVID-19 Vaccine) (unknown route) dosage was changed to 1 dosage form. In April 2021, the patient experienced COVID-19 (COVID) (seriousness criterion hospitalization) and DRUG INEFFECTIVE (Lack of drug effect). The patient was hospitalized for 20 days due to COVID-19. The patient was treated with OXYGEN ongoing since an unknown date for Difficulty breathing, at a dose of UNK, one time dose. At the time of the report, COVID-19 (COVID) outcome was unknown and DRUG INEFFECTIVE (Lack of drug effect) had resolved.      DIAGNOSTIC RESULTS (normal ranges are provided in parenthesis if available): On 09-May-2021, Oxygen saturation: low (Low) Low. On 22-May-2021, Oxygen saturation: 83 (Low) 83.         The patient said the symptoms started on April 28th with fever, chills, aches, body aches and a slight cough. On 29-Apr-2021, the patient took a test locally on a rite aid and it came back negative. On 09-May2021,  patient could not breath, was struggling to breath because oxygen level was really low. The patient was admitted on Mother's day, May 9th, for the first time and was discharged on the 12th of May. The patient was then admitted again on the 22nd of May as the "saturation level was 83 of oxygen". The patient was discharged on June 2nd and was sent home with oxygen. The patient was still using oxygen but only at night. The patient said that it was determined the Rituxan on it's system did not allow the vaccine to act. The Rituxan depletes B and T cells causing to be immunosuppressed. The patient was told this after being there one week and after they run all kind of tests, bloodwork's, immunoglobulins, and COVID-19 Antibodies which it said it was non reactive and that was done several times. Symptoms lasted until first week of August and still has some oxygen loss on aerobic exercising. The patient visited doctor and going through all kind of pulmonary testing's. Other treatment medications included Rendezivir, Monoclonal antibody, unspecified steroids and unspecified antibiotic.  Company comment: This case of drug ineffective, concerns a 65-year-old female subject with a history of rheumatoid arthritis, who experienced the serious unexpected event of COVID-19. The event occurred in an unknown date of the following month after the second dose of Spikevax. The rechallenge was not applicable as no additional dose is expected to be given. The benefit-risk relationship of Spikevax is not affected by this report. More information has been requested about patient´s immunocompromise and the possible indication of a third dose.; Sender's Comments: This case of drug ineffective, concerns a 65-year-old female subject with a history of rheumatoid arthritis, who experienced the serious unexpected event of COVID-19. The event occurred in an unknown date of the following month after the second dose of Spikevax. The rechallenge was not applicable as no additional dose is expected to be given. The benefit-risk relationship of Spikevax is not affected by this report. More information has been requested about patient´s immunocompromise and the possible indication of a third dose.