ATYPICAL CHEST PAIN; This 63 year old, male subject  was participating in a study and experienced atypical chest pain.  The subject's medical history, as provided by the investigator, included HIV infection, hypertension, diabetes, hepatitis C, ulcerative colitis, and gastroesophageal reflux disease. Concomitant medications reported included paracetamol, lisinopril, losartan, bumetanide, pantoprazole, ustekinumab, insulin, bictegravir sodium-emtricitabine-tenofovir alafenamide fumarate, and budesonide.  Prior to event onset, the subject received intramuscular mRNA-1273 (Booster, Dose 3) for SARS-CoV-2 vaccination on 29 Oct 2021, approximately 1 month and 8 days before onset of the event.  On 06 Dec 2021, the subject experienced atypical chest pain. Subject reported intermittent mild to moderate chest pain that was relieved by pain medication. Treatment for the event included unspecified pain medication. Subject has not sought medical attention, and has refused to seek emergency care.   The subject received all scheduled doses of study drug prior to the event; therefore, action taken with study drug in response to the event was not applicable.   The event, atypical chest pain, was reported as not resolved.   The investigator assessed the event, atypical chest pain, as related to study drug and not related to study procedure.  Company comment: This case concerns a 63-year-old, male subject with a medical history of HIV infection, hypertension, diabetes, hepatitis C, ulcerative colitis, and gastroesophageal reflux disease, who experienced the unlisted event of atypical chest pain. The event occurred 1 year 1 month 23 days after the first dose of mRNA-1273 and 1 month and 8 days after the booster and last dose. The subject received all scheduled doses of study drug prior to the event; therefore, action taken with study vaccine in response to the event was not applicable. The event, atypical chest pain, was reported as not resolved. The event was considered related to the study vaccine in agreement with the investigator based on temporal association in the absence of alternative explanations. Features of the pain, supportive diagnostic procedures, treatment an updated outcome, that would contribute the assessment of the case, were not provided. Additional information was requested.  Analysis of Similar Events: On 12 Jan 2022, the safety database was searched for events similar to Chest pain using the following search criteria: PT: Chest pain, Non cardiac chest pain, and Angina pectoris.  As of 12-Jan-2022 under IND for mRNA-1273, 33 similar events were retrieved, including the current index case.; Reporter's Comments: This case concerns a 63-year-old, male subject with a medical history of HIV infection, hypertension, diabetes, hepatitis C, ulcerative colitis, and gastroesophageal reflux disease, who experienced the unlisted event of atypical chest pain. The event occurred 1 year 1 month 23 days after the first dose of mRNA-1273 and 1 month and 8 days after the booster and last dose. The subject received all scheduled doses of study drug prior to the event; therefore, action taken with study vaccine in response to the event was not applicable. The event, atypical chest pain, was reported as not resolved. The event was considered related to the study vaccine in agreement with the investigator based on temporal association in the absence of alternative explanations. Features of the pain, supportive diagnostic procedures, treatment an updated outcome, that would contribute the assessment of the case, were not provided. Additional information was requested.