The patient says that she thinks that she has Multiple Sclerosis because of the two different Covid-19 vaccines; Mixed vaccine series for primary series; This spontaneous case was reported by a consumer and describes the occurrence of MULTIPLE SCLEROSIS (The patient says that she thinks that she has Multiple Sclerosis because of the two different Covid-19 vaccines) in a female patient of an unknown age who received mRNA-1273 (Spikevax) for COVID-19 vaccination. The occurrence of additional non-serious events is detailed below.    Co-suspect product included non-company product TOZINAMERAN (PFIZER BIONTECH COVID-19 VACCINE) for COVID-19 vaccination.    No Medical History information was reported.   On an unknown date, the patient received second dose of mRNA-1273 (Spikevax) (unknown route) 1 dosage form and first dose of TOZINAMERAN (PFIZER BIONTECH COVID-19 VACCINE) (unknown route) 1 dosage form. On an unknown date, the patient experienced MULTIPLE SCLEROSIS (The patient says that she thinks that she has Multiple Sclerosis because of the two different Covid-19 vaccines) (seriousness criterion medically significant) and INTERCHANGE OF VACCINE PRODUCTS (Mixed vaccine series for primary series). At the time of the report, MULTIPLE SCLEROSIS (The patient says that she thinks that she has Multiple Sclerosis because of the two different Covid-19 vaccines) and INTERCHANGE OF VACCINE PRODUCTS (Mixed vaccine series for primary series) outcome was unknown.            Concomitant product use was not provided by the reporter.   The first time that the patient went to get a Covid-19 vaccine she received the Pfizer Covid-19 vaccine. The patient says that she received the Moderna Covid-19 vaccine for her second dose. The patient says that her vaccination card indicates that she received the two different manufacturers vaccines. Reporter stated patient was very tearful and emotional on the phone. The patient says that she thinks that she had Multiple Sclerosis because of the two different Covid-19 vaccines, and that she had contacted her states Department of Health. The patient then said that she went to the Emergency Room because she felt like she has Multiple Sclerosis. The Emergency Room referred the patient to her Doctor.  No treatment information was provided. Company comment: This spontaneous case concerns a female patient of an unknown age with no medical history reported, who experienced serious (medically significant) unexpected event of multiple sclerosis (AESI), which occurred on an unknown date after administration of the 2nd dose of mRNA-1273 vaccine. Interchange of vaccine products was considered an additional event. The patient did not provide Adverse Events or Side Effects for either vaccine. She thinks that she has Multiple Sclerosis because of the two different Covid-19 vaccines and she said that she went to the Emergency Room because she felt like she has Multiple Sclerosis. No further information regarding the clinical course and treatment of the event was provided. The benefit-risk relationship of the mRNA-1273 vaccine is not affected by this report.; Sender's Comments: This spontaneous case concerns a female patient of an unknown age with no medical history reported, who experienced serious (medically significant) unexpected event of multiple sclerosis (AESI), which occurred on an unknown date after administration of the 2nd dose of mRNA-1273 vaccine. Interchange of vaccine products was considered an additional event. The patient did not provide Adverse Events or Side Effects for either vaccine. She thinks that she has Multiple Sclerosis because of the two different Covid-19 vaccines and she said that she went to the Emergency Room because she felt like she has Multiple Sclerosis. No further information regarding the clinical course and treatment of the event was provided. The benefit-risk relationship of the mRNA-1273 vaccine is not affected by this report.