RIGHT KNEE REPLACED; ARM FELT HEAVY AND STIFF; ARM FELT HEAVY AND STIFF; Interchange of vaccine products; Revaccination with different COVID-19 vaccine; This spontaneous case was reported by a consumer and describes the occurrence of KNEE ARTHROPLASTY (RIGHT KNEE REPLACED) in an adult female patient who received mRNA-1273 (Spikevax) for COVID-19 prophylaxis. The occurrence of additional non-serious events is detailed below.    Co-suspect products included non-company products ADALIMUMAB (HUMIRA) for Rheumatoid arthritis and TOZINAMERAN (PFIZER BIONTECH COVID-19 VACCINE) for COVID-19 vaccination.    Concurrent medical conditions included Rheumatoid arthritis (Moderate to Severe).   On 01-Apr-2021, the patient received dose of TOZINAMERAN (PFIZER BIONTECH COVID-19 VACCINE) (Intramuscular) 1 dosage form. On 22-Apr-2021, received dose of TOZINAMERAN (PFIZER BIONTECH COVID-19 VACCINE) (Intramuscular) dosage was changed to 1 dosage form. On 19-Dec-2021, received dose of TOZINAMERAN (PFIZER BIONTECH COVID-19 VACCINE) (Intramuscular) dosage was changed to 1 dosage form. On an unknown date, the patient received second dose of mRNA-1273 (Spikevax) (Intramuscular) 1 dosage form On an unknown date, received first dose of mRNA-1273 (Spikevax) (Intramuscular) dosage was changed to 1 dosage form and ADALIMUMAB (HUMIRA) (Subcutaneous) at an unspecified dose., ADALIMUMAB (HUMIRA) (Subcutaneous) dosage was changed to at an unspecified dose and ADALIMUMAB (HUMIRA) (Subcutaneous) dosage was changed to at an unspecified dose. On an unknown date, the patient experienced KNEE ARTHROPLASTY (RIGHT KNEE REPLACED) (seriousness criterion medically significant), LIMB DISCOMFORT (ARM FELT HEAVY AND STIFF), MUSCULOSKELETAL STIFFNESS (ARM FELT HEAVY AND STIFF), INTERCHANGE OF VACCINE PRODUCTS (Interchange of vaccine products) and COVID-19 IMMUNISATION (Revaccination with different COVID-19 vaccine). At the time of the report, KNEE ARTHROPLASTY (RIGHT KNEE REPLACED) had not resolved, LIMB DISCOMFORT (ARM FELT HEAVY AND STIFF) and MUSCULOSKELETAL STIFFNESS (ARM FELT HEAVY AND STIFF) had resolved and INTERCHANGE OF VACCINE PRODUCTS (Interchange of vaccine products) and COVID-19 IMMUNISATION (Revaccination with different COVID-19 vaccine) outcome was unknown.            No concomitant medication was reported. On an unknown date, patient received 1st dose and 2nd dose COVID-19 Vaccine manufactured by Moderna. On unknown dates, the patient experienced RIGHT KNEE REPLACED, SECOND DOSE OF MODERNA MADE ARM FELT HEAVY AND STIFF. On 01-Apr-2021, patient received 1st dose COVID-19 Vaccine manufactured by Pfizer/BioNTech, on 22-Apr-2021, patient received 2nd dose and the patient received booster dose of Pfizer/BioNTech. In 2021, the patient experienced FATIGUE and MILD HEADACHE. In 2021, the FATIGUE and MILD HEADACHE resolved. On unknown dates, SECOND DOSE OF MODERNA MADE ARM FELT HEAVY AND STIFF, BOOSTER PFIZER COVID-19 VACCINE CAUSED SORE ARM AND FATIGUED and COVID-19 resolved. The patient had right knee replaced and was off HUMIRA for a week. Second dose of Moderna made her arm felt heavy and stiff. Booster shot caused fatigue and mild headache. She started feeling sick two weeks ago had sinus, headache, numbness, and coughing previously had Covid and thought she had it again.  This case was identified as part of a retrospective clean-up activity where certain emails received in the Moderna mailbox were missed to be booked-in.  Company Comment: This is a Spontaneous case reported by a consumer, concerning an adult female patient, with relevant medical condition of rheumatoid arthritis, who experienced the unexpected and serious (due to medically significant) event of Knee arthroplasty (reported as right knee replaced), which occurred related to an unspecified dose of mRNA-1273 vaccine. Co-suspect products included non-company product Adalimumab for rheumatoid arthritis, and Pfizer vaccine against COVID-19. No information disclosed about diagnostic tests performed or treatments received. At the time of the report, the event had not resolved. Underlying rheumatoid arthritis could be a confounding factor for knee arthroplasty. The benefit-risk relationship of mRNA-1273 vaccine, is not affected by this report.   Most recent FOLLOW-UP information incorporated above includes: On 28-Dec-2021: Significant follow-up received: Humira batch number added. information about booster dose was updated. Causality for the event Total knee replacement was updated for moderna vaccine. On 19-Jan-2022: Significant follow up received : Total knee replacement outcome updated. Humira batch number added. Information updated for booster.; Sender's Comments: This is a Spontaneous case reported by a consumer, concerning an adult female patient, with relevant medical condition of rheumatoid arthritis, who experienced the unexpected and serious (due to medically significant) event of Knee arthroplasty (reported as right knee replaced), which occurred related to an unspecified dose of mRNA-1273 vaccine. Co-suspect products included non-company product Adalimumab for rheumatoid arthritis, and Pfizer vaccine against COVID-19. No information disclosed about diagnostic tests performed or treatments received. At the time of the report, the event had not resolved. Underlying rheumatoid arthritis could be a confounding factor for knee arthroplasty. The benefit-risk relationship of mRNA-1273 vaccine, is not affected by this report.