PNEUMONIA; LOCULATED PLEURAL EFFUSION LEFT; This 70-year-old, male subject (US3922011) was participating in A Phase 3, Randomized, Stratified, Observer-Blind, Placebo-Controlled Study.  The subject's medical history, as provided by the investigator, included squamous cell carcinoma, gout (bilateral big toes), middle finger injury, lymphadenectomy right side neck (due to squamous cell carcinoma on tonsil), tonsillectomy, middle finger injury repair, edema bilateral feet, stroke, hypothyroidism, gastroesophageal reflux disease (GERD), post-traumatic stress disorder, psoriasis, eczema, and atrial fibrillation. Concomitant medications reported included allopurinol, indomethacin, rivaroxaban, levothyroxine sodium, escitalopram, pantoprazole, clobetasol propionate, terbinafine, and buspirone.     The subject was randomized to receive intramuscular Placebo (dosed on 19 Aug 2020 and 17 Sep 2020) and was unblinded on 25 Mar 2021. The subject consented to receive mRNA-1273 for SARS-CoV-2 vaccination after being unblinded and, prior to event onset, the subject received mRNA-1273 (Dose 2) on 19 Apr 2021, approximately 6 months and 21 days before onset of the event. The subject received booster dose of mRNA-1273 on 30 Nov 2021.  On 08 Nov 2021, the subject developed loculated pleural effusion left.  On 07 Dec 2021, the subject experienced pneumonia.  On 08 Dec 2021, the subject was admitted to the hospital.  On 21 Dec 2021, the subject was discharged from the hospital.  The subject received all scheduled doses of study drug prior to the event, pneumonia; therefore, action taken with study drug in response to the event, pneumonia, was not applicable.  No action was taken with the study drug in response to the event of loculated pleural effusion left.  The event, pneumonia, was reported as resolved on 21 Dec 2021.  The event, loculated pleural effusion left, was reported as not resolved.    The investigator assessed the events, pneumonia and loculated pleural effusion left, as not related to study drug and not related to study procedure.  Follow-up received on 15 Dec 2021 included updated study drug booster dose information and event outcome.  Follow-up received on 18 Jan 2022 included updated date of hospital admission and hospital discharge date.  Follow-up received on 17 Feb 2022 and 21 Feb 2022 included final event outcome, event end date, and new event details.  Company Comment: This case concerns a 70-year-old, male subject with a history of squamous cell carcinoma, gout (bilateral big toes), lymphadenectomy right side neck (due to squamous cell carcinoma on tonsil), tonsillectomy, stroke, hypothyroidism, gastroesophageal reflux disease (GERD), post-traumatic stress disorder, and atrial fibrillation, among others, who experienced the unexpected events of pneumonia and loculated pleural effusion left. The event pneumonia occurred approximately 8 months 11 days after the first dose of mRNA-1273 and 8 days after the booster and most recent dose of mRNA-1273. The event loculated pleural effusion left occurred approximately 1 year 2 months after the first dose of mRNA-1273 and 6 months 21 days after the booster and most recent dose of mRNA-1273.  The event pneumonia was reported as resolved. The event loculated pleural effusion left was reported as not resolved.  The events were considered unrelated to the study vaccine in agreement with the Investigator. The event might be explained by underlying comorbidities.; Reporter's Comments: Company Comment: This case concerns a 70-year-old, male subject with a history of squamous cell carcinoma, gout (bilateral big toes), lymphadenectomy right side neck (due to squamous cell carcinoma on tonsil), tonsillectomy, stroke, hypothyroidism, gastroesophageal reflux disease (GERD), post-traumatic stress disorder, and atrial fibrillation, among others, who experienced the unexpected events of pneumonia and loculated pleural effusion left. The event pneumonia occurred approximately 8 months 11 days after the first dose of mRNA-1273 and 8 days after the booster and most recent dose of mRNA-1273. The event loculated pleural effusion left occurred approximately 1 year 2 months after the first dose of mRNA-1273 and 6 months 21 days after the booster and most recent dose of mRNA-1273.  The event pneumonia was reported as resolved. The event loculated pleural effusion left was reported as not resolved.  The events were considered unrelated to the study vaccine in agreement with the Investigator. The event might be explained by underlying comorbidities.