Palpitations; lost their appetite; Brain fog and feeling of confuse; Pain all over both arms, legs and chest  got worst.; On the night of 10Feb2022 were sick, got  fever and chills.; On the night of 10Feb2022 were sick, got  fever and chills.; musculoskeletal chest pain; Still has jaw and neck soreness.; Had little round  bumps, that have shrink and multiplied.; Still has jaw and neck soreness.; Acute chest syndrome/ Chest discomfort/ Dyspnoea exertional; This spontaneous case was reported by a nurse and describes the occurrence of ACUTE CHEST SYNDROME (Acute chest syndrome/ Chest discomfort/ Dyspnoea exertional) in a 38-year-old male patient who received mRNA-1273 (Spikevax) for COVID-19 prophylaxis. The occurrence of additional non-serious events is detailed below.     Patient had no allergies.  The patient's past medical history included COVID-19 (Had COVID-19 before getting vaccinated and were hospitalized still has it) in January 2022. Concomitant products included INSULIN for an unknown indication.    On 10-Feb-2022, the patient received first dose of mRNA-1273 (Spikevax) (Intramuscular) 1 dosage form. On 10-Feb-2022, the patient experienced DECREASED APPETITE (lost their appetite), FEELING ABNORMAL (Brain fog and feeling of confuse), PAIN (Pain all over both arms, legs and chest  got worst.), CHILLS (On the night of 10Feb2022 were sick, got  fever and chills.) and PYREXIA (On the night of 10Feb2022 were sick, got  fever and chills.). In February 2022, the patient experienced ACUTE CHEST SYNDROME (Acute chest syndrome/ Chest discomfort/ Dyspnoea exertional) (seriousness criterion medically significant), NECK PAIN (Still has jaw and neck soreness.), NODULE (Had little round  bumps, that have shrink and multiplied.), PAIN IN JAW (Still has jaw and neck soreness.) and MUSCULOSKELETAL CHEST PAIN (musculoskeletal chest pain). On an unknown date, the patient experienced PALPITATIONS (Palpitations). At the time of the report, ACUTE CHEST SYNDROME (Acute chest syndrome/ Chest discomfort/ Dyspnoea exertional), DECREASED APPETITE (lost their appetite), NODULE (Had little round  bumps, that have shrink and multiplied.), PALPITATIONS (Palpitations), FEELING ABNORMAL (Brain fog and feeling of confuse), PAIN (Pain all over both arms, legs and chest  got worst.), MUSCULOSKELETAL CHEST PAIN (musculoskeletal chest pain), CHILLS (On the night of 10Feb2022 were sick, got  fever and chills.) and PYREXIA (On the night of 10Feb2022 were sick, got  fever and chills.) outcome was unknown and NECK PAIN (Still has jaw and neck soreness.) and PAIN IN JAW (Still has jaw and neck soreness.) had not resolved.      DIAGNOSTIC RESULTS (normal ranges are provided in parenthesis if available): In January 2022, SARS-CoV-2 test: positive (Positive) Positive.     The action taken with mRNA-1273 (Spikevax) (Intramuscular) was unknown.   For mRNA-1273 (Spikevax) (Intramuscular), the reporter did not provide any causality assessments.   Concomitant medication included cholesterol medicine. No treatment information was provided. On Jan-2022 patient had COVID and it still has. No other vaccine given within 1 month prior to Moderna COVID-19 vaccine. Patient did not seek medical care for AE. Patient had chest pain, dyspnea and palpitations.  Company comment: This spontaneous case concerns a male patient aged 38 years with relevant medical history of covid infection in Jan2022 reported, who experienced the unexpected serious (medically significant) event of Acute chest syndrome on unknown date after receiving the first dose of mRNA-1273 vaccine in the covid 19 vaccination series.  He also had multiple non serious events like Decreased appetite, Neck pain, Nodule, Pain in jaw, Feeling abnormal, Pain, Musculoskeletal chest pain, Palpitations, Chills and Pyrexia. It was reported patient was hospitalized for covid before vaccination. After discharge had his first dose of mRNA-1273 vaccine experienced brain fog, worsening of pain in arms, legs and chest. The same night he was sick with fever and chills, decreased appetite along with sore neck and jaw. He also had multiple round bumps that have shrunk. No further clinical course, lab results or treatment details were reported.  Relevant medical history remains a confounder to the event Acute chest syndrome. The benefit-risk relationship of mRNA-1273 Vaccine is not affected by this report. Event seriousness assessed per medical judgement.   Reporter did not allow further contact; Sender's Comments: This spontaneous case concerns a male patient aged 38 years with relevant medical history of covid infection in Jan2022 reported, who experienced the unexpected serious (medically significant) event of Acute chest syndrome on unknown date after receiving the first dose of mRNA-1273 vaccine in the covid 19 vaccination series.  He also had multiple non serious events like Decreased appetite, Neck pain, Nodule, Pain in jaw, Feeling abnormal, Pain, Musculoskeletal chest pain, Palpitations, Chills and Pyrexia. It was reported patient was hospitalized for covid before vaccination. After discharge had his first dose of mRNA-1273 vaccine experienced brain fog, worsening of pain in arms, legs and chest. The same night he was sick with fever and chills, decreased appetite along with sore neck and jaw. He also had multiple round bumps that have shrunk. No further clinical course, lab results or treatment details were reported.  Relevant medical history remains a confounder to the event Acute chest syndrome. The benefit-risk relationship of mRNA-1273 Vaccine is not affected by this report. Event seriousness assessed per medical judgement.