immune system was not working; everything(blood parameters) went down, blood levels went really low; Missed the 2nd dose of Moderna vaccine because of hospitalization; weakness; fullness following eating little; felt really bad; nausea; stools were really black in color; This spontaneous case was reported by a consumer (subsequently medically confirmed) and describes the occurrence of IMMUNE SYSTEM DISORDER (immune system was not working) and VOLUME BLOOD DECREASED (everything(blood parameters) went down, blood levels went really low) in a 61-year-old female patient who received mRNA-1273 (Moderna COVID-19 Vaccine) (batch no. 018B21A) for COVID-19 vaccination. The occurrence of additional non-serious events is detailed below.     Concomitant products included FLUTICASONE for Allergy, AMLODIPINE for Blood pressure management, ONDANSETRON for Nausea, SUCRALFATE for Stomach ulcer, SPIRONOLACTONE for Water retention, CLOPIDOGREL, GABAPENTIN and MONTELUKAST SODIUM (MONTELUKAST OD) for an unknown indication.    On 27-Mar-2021, the patient received first dose of mRNA-1273 (Moderna COVID-19 Vaccine) (Intramuscular) 1 dosage form. On 29-Mar-2021, the patient experienced FAECES DISCOLOURED (stools were really black in color), ASTHENIA (weakness), ABDOMINAL DISTENSION (fullness following eating little), FEELING ABNORMAL (felt really bad) and NAUSEA (nausea). On 15-Apr-2021, the patient experienced IMMUNE SYSTEM DISORDER (immune system was not working) (seriousness criterion hospitalization) and VOLUME BLOOD DECREASED (everything(blood parameters) went down, blood levels went really low) (seriousness criterion hospitalization). On 24-Apr-2021, the patient experienced PRODUCT DOSE OMISSION ISSUE (Missed the 2nd dose of Moderna vaccine because of hospitalization). The patient was hospitalized from 15-Apr-2021 to 18-Apr-2021 due to IMMUNE SYSTEM DISORDER and VOLUME BLOOD DECREASED. On 24-Apr-2021, PRODUCT DOSE OMISSION ISSUE (Missed the 2nd dose of Moderna vaccine because of hospitalization) had resolved. At the time of the report, IMMUNE SYSTEM DISORDER (immune system was not working), VOLUME BLOOD DECREASED (everything(blood parameters) went down, blood levels went really low), FAECES DISCOLOURED (stools were really black in color), ASTHENIA (weakness), ABDOMINAL DISTENSION (fullness following eating little), FEELING ABNORMAL (felt really bad) and NAUSEA (nausea) outcome was unknown.      DIAGNOSTIC RESULTS (normal ranges are provided in parenthesis if available): On 15-Apr-2021, Vitamin B12: decreased not producing enough B12 and everything(blood parameter's ) went down.     The action taken with mRNA-1273 (Moderna COVID-19 Vaccine) (Intramuscular) was unknown.       Patient received B12 shot at the hospital and got  discharged from the hospital on 18Apr2021 with discharge prescription for B12 Shot to be continued. Patient reported, Doctor at the hospital quoted, that, "thought of giving the blood transfusion at one point since the blood levels went really low  Company Comment: Based on current available information and the temporal association between product use and the start date of the events a causal relationship cannot be excluded.; Sender's Comments: Based on current available information and the temporal association between product use and the start date of the events a causal relationship cannot be excluded.