became anemic and lost a lot of blood during these months; I'm concerned because it's a lot/it'll leak like a water faucet/also had a lot of clots / it lasted for 22 days; chest problems; Then 3-5 days later, her cycle came back /  It'll stop for 3-5 days, but it'll come around longer; Activities of daily living impaired; itchy; swelling in my arm where I got the shot; red and really swollen; received the first dose of Moderna COVID19 Vaccine on 24Apr2021, did not receive the second dose yet; menstrual cycle wasn't due yet /  since 24Apr2021, I've been on my cycle on and off; This spontaneous case was reported by a consumer and describes the occurrence of BLOOD LOSS ANAEMIA (became anemic and lost a lot of blood during these months), HEAVY MENSTRUAL BLEEDING (I'm concerned because it's a lot/it'll leak like a water faucet/also had a lot of clots / it lasted for 22 days) and CHEST DISCOMFORT (chest problems) in a 42-year-old female patient who received mRNA-1273 (Moderna COVID-19 Vaccine) (batch no. 007C21A) for COVID-19 vaccination. The occurrence of additional non-serious events is detailed below.     No Medical History information was reported.    On 24-Apr-2021, the patient received first dose of mRNA-1273 (Moderna COVID-19 Vaccine) (Intramuscular) 1 dosage form. On 24-Apr-2021, the patient experienced MENSTRUATION IRREGULAR (menstrual cycle wasn't due yet /  since 24Apr2021, I've been on my cycle on and off) and PRODUCT DOSE OMISSION ISSUE (received the first dose of Moderna COVID19 Vaccine on 24Apr2021, did not receive the second dose yet). On 26-Apr-2021, the patient experienced VACCINATION SITE PRURITUS (itchy), VACCINATION SITE SWELLING (swelling in my arm where I got the shot) and VACCINATION SITE ERYTHEMA (red and really swollen). On an unknown date, the patient experienced BLOOD LOSS ANAEMIA (became anemic and lost a lot of blood during these months) (seriousness criteria hospitalization and medically significant), HEAVY MENSTRUAL BLEEDING (I'm concerned because it's a lot/it'll leak like a water faucet/also had a lot of clots / it lasted for 22 days) (seriousness criteria hospitalization and medically significant), CHEST DISCOMFORT (chest problems) (seriousness criterion hospitalization), POLYMENORRHOEA (Then 3-5 days later, her cycle came back /  It'll stop for 3-5 days, but it'll come around longer) and LOSS OF PERSONAL INDEPENDENCE IN DAILY ACTIVITIES (Activities of daily living impaired). The patient was hospitalized on 19-Aug-2021 due to BLOOD LOSS ANAEMIA, CHEST DISCOMFORT and HEAVY MENSTRUAL BLEEDING. On 24-Apr-2021, PRODUCT DOSE OMISSION ISSUE (received the first dose of Moderna COVID19 Vaccine on 24Apr2021, did not receive the second dose yet) had resolved. On 02-Aug-2021, VACCINATION SITE PRURITUS (itchy), VACCINATION SITE SWELLING (swelling in my arm where I got the shot) and VACCINATION SITE ERYTHEMA (red and really swollen) had resolved. At the time of the report, BLOOD LOSS ANAEMIA (became anemic and lost a lot of blood during these months), HEAVY MENSTRUAL BLEEDING (I'm concerned because it's a lot/it'll leak like a water faucet/also had a lot of clots / it lasted for 22 days) and CHEST DISCOMFORT (chest problems) had not resolved and MENSTRUATION IRREGULAR (menstrual cycle wasn't due yet /  since 24Apr2021, I've been on my cycle on and off), POLYMENORRHOEA (Then 3-5 days later, her cycle came back /  It'll stop for 3-5 days, but it'll come around longer) and LOSS OF PERSONAL INDEPENDENCE IN DAILY ACTIVITIES (Activities of daily living impaired) outcome was unknown.        The action taken with mRNA-1273 (Moderna COVID-19 Vaccine) (Intramuscular) was unknown.       No concomitant medications are provided. The patient reports that she put Vaseline on her arm and covered her arm, so that she wouldn't scratch it..Patient was admitted to hospital after chest discomfort on 19 -Aug-2021 and received  blood transfusion for the next 2 days. Based on the current available information and temporal association between the use of the product and the start date of events, a causal relationship cannot be excluded. Further information is requested.   Most recent FOLLOW-UP information incorporated above includes: On 01-Sep-2021: Follow-up received on 01-Sep-2021: Patient demographic updated. Events Blood loss anemia, Heavy menstrual bleeding and Chest discomfort added with seriousness hospitalization. On 09-Sep-2021: Followup received, contains no new information.; Sender's Comments: Based on the current available information and temporal association between the use of the product and the start date of events, a causal relationship cannot be excluded. Further information is requested.