Right Knee pain; Difficulty in walking; Interchange of vaccine; Achy arm; left knee pain / left Knee pain worsened; This spontaneous case was reported by a consumer and describes the occurrence of ARTHRALGIA (Right Knee pain) in a 73-year-old female patient who received mRNA-1273 (Moderna COVID-19 Vaccine) for COVID-19 vaccination. The occurrence of additional non-serious events is detailed below.    Co-suspect product included non-company product RISANKIZUMAB (SKYRIZI [RISANKIZUMAB]) for Plaque psoriasis.    The patient's past medical history included Psoriasis and Knee replacement in October 2021. Concurrent medical conditions included Knee pain. Concomitant products included TOZINAMERAN (PFIZER BIONTECH COVID-19 VACCINE) for COVID-19 vaccination.   On an unknown date, the patient received fourth dose of mRNA-1273 (Moderna COVID-19 Vaccine) (Intramuscular) 1 dosage form and RISANKIZUMAB (SKYRIZI [RISANKIZUMAB]) (Subcutaneous) at an unspecified dose. On an unknown date, RISANKIZUMAB (SKYRIZI [RISANKIZUMAB]) (Subcutaneous) dosage was changed to at an unspecified dose and RISANKIZUMAB (SKYRIZI [RISANKIZUMAB]) (Subcutaneous) dosage was changed to at an unspecified dose. On an unknown date, the patient experienced ARTHRALGIA (Right Knee pain) (seriousness criterion medically significant), GAIT DISTURBANCE (Difficulty in walking), INTERCHANGE OF VACCINE PRODUCTS (Interchange of vaccine), PAIN IN EXTREMITY (Achy arm) and ARTHRALGIA (left knee pain / left Knee pain worsened). At the time of the report, ARTHRALGIA (Right Knee pain), GAIT DISTURBANCE (Difficulty in walking) and INTERCHANGE OF VACCINE PRODUCTS (Interchange of vaccine) outcome was unknown, PAIN IN EXTREMITY (Achy arm) had resolved and ARTHRALGIA (left knee pain / left Knee pain worsened) had not resolved.            Patient had been having knee issues for years. Patient had right and left knee pain and needed to replace that one. In Oct 2021, the patient had right knee replacement and knee was healing well. Patient had warm pool exercises to help with recovery. Patient left knee had worsened, and it was difficult to walk. Had worsened even more the last two weeks and hurts every hour of the day. Patient had a horrible head cold since 02 Feb 2022. Patient had achy arm after second booster of Moderna, first three vaccines were Pfizer with no arm pain. It was unknown if patient was enrolled in a COVID-19 Vaccine Trial. No treatment medications were provided Company comment: This spontaneous case concerns a 73-year-old female patient, with medical history of knee pain with a knee replacement during the last year, who experienced the serious (due to medically significant) unexpected event of ARTHRALGIA, among other non-serious events. The event and the vaccination with mRNA-1273 vaccine, considered as the fourth dose of the vaccine schedule, were reported with no onset date; hence latency cannot be assessed. As per source document, she received previously three doses of TOZINAMERAN (PFIZER BIONTECH COVID-19 VACCINE): interchange of vaccine products. Patient´s medical history of knee pain with a knee replacement remains as confounders for the event. It was reported she had been having knee issues for years, it had worsened and hurts every hour of the day with difficulty walking. The benefit-risk relationship of the mRNA-1273 vaccine is not affected by this report.   Most recent FOLLOW-UP information incorporated above includes: On 21-Jun-2022: Significant Follow-up received: Events added and The event of "RIGHT KNEE AND LEFT KNEE PAIN" was amended to "RIGHT KNEE PAIN".; Sender's Comments: This spontaneous case concerns a 73-year-old female patient, with medical history of knee pain with a knee replacement during the last year, who experienced the serious (due to medically significant) unexpected event of ARTHRALGIA, among other non-serious events. The event and the vaccination with mRNA-1273 vaccine, considered as the fourth dose of the vaccine schedule, were reported with no onset date; hence latency cannot be assessed. As per source document, she received previously three doses of TOZINAMERAN (PFIZER BIONTECH COVID-19 VACCINE): interchange of vaccine products. Patient´s medical history of knee pain with a knee replacement remains as confounders for the event. It was reported she had been having knee issues for years, it had worsened and hurts every hour of the day with difficulty walking. The benefit-risk relationship of the mRNA-1273 vaccine is not affected by this report.