This spontaneous case was reported by an other health care professional (subsequently medically confirmed) and describes the occurrence of DEHYDRATION (Severe Dehydration) in a 72-year-old female patient who received mRNA-1273 (Moderna COVID-19 Vaccine) (batch nos. 011A21A and 012M20A) for COVID-19 vaccination. The occurrence of additional non-serious events is detailed below.    Co-suspect product included non-company product ADALIMUMAB (HUMIRA) for Rheumatoid arthritis.    The patient's past medical history included Alcohol use in 1966, Tobacco user in 1968, Dehydration (sever dehydration) in September 2019, Hypertension (severe hypertension) and Cataract operation (Bilateral cataract surgery). Concurrent medical conditions included Rheumatoid arthritis, High cholesterol, Prediabetes (Prediabetes type 2), Antidepressant therapy (Anti-depressant use) and Acid reflux (esophageal). Concomitant products included OMEPRAZOLE for Acid reflux (oesophageal), BUPROPION and DULOXETINE HYDROCHLORIDE (CYMBALTA) for Depression, PRAVASTATIN for High cholesterol, HYDROCHLOROTHIAZIDE and LOSARTAN for Hypertension, HYDROXYCHLOROQUINE PHOSPHATE (PLAQUENIL [HYDROXYCHLOROQUINE PHOSPHATE]) and PREDNISONE for Rheumatoid arthritis, METFORMIN for Type 2 diabetes mellitus.   On 10-Oct-2019, the patient started ADALIMUMAB (HUMIRA) (unknown route) Citrate Free (40 mg,1 in 1 wk). On 29-Jan-2021, the patient received first dose of mRNA-1273 (Moderna COVID-19 Vaccine) (Intramuscular) 1 dosage form. On 26-Feb-2021, received second dose of mRNA-1273 (Moderna COVID-19 Vaccine) (Intramuscular) dosage was changed to 1 dosage form. On 27-Feb-2021, the patient experienced HYPERSOMNIA (Sleep a lot than usual) and HEADACHE (Headache). On 01-Mar-2021, the patient experienced DEHYDRATION (Severe Dehydration) (seriousness criterion hospitalization prolonged). In March 2021, the patient experienced AGE-RELATED MACULAR DEGENERATION (WORSENED AGE RELATED MACULAR DEGENERATION). On an unknown date, the patient experienced HYPOPHAGIA (did not eat or drink). The patient was hospitalized from 03-Mar-2021 to 06-Mar-2021 due to DEHYDRATION. On 01-Mar-2021, HYPERSOMNIA (Sleep a lot than usual) and HEADACHE (Headache) had resolved. On 04-Mar-2021, DEHYDRATION (Severe Dehydration) had resolved. At the time of the report, HYPOPHAGIA (did not eat or drink) outcome was unknown and AGE-RELATED MACULAR DEGENERATION (WORSENED AGE RELATED MACULAR DEGENERATION) was resolving.      DIAGNOSTIC RESULTS (normal ranges are provided in parenthesis if available): In March 2021, Blood pressure measurement: normal. In March 2021, Computerised tomogram: no significant findings No significant findings. In March 2021, Urine analysis: no significant findings No significant findings.     For mRNA-1273 (Moderna COVID-19 Vaccine) (Intramuscular), the reporter considered DEHYDRATION (Severe Dehydration) and HEADACHE (Headache) to be probably related, HYPERSOMNIA (Sleep a lot than usual) to be possibly related and AGE-RELATED MACULAR DEGENERATION (WORSENED AGE RELATED MACULAR DEGENERATION) to be not related. No further causality assessment was provided for HYPOPHAGIA (did not eat or drink).    The patient was treated with (TYLENOL).  action taken with mRNA-1273 not applicable  Based on the current available information and temporal association between the use of the product and the start date of the events (hypophagia, headache, hypersomnia and dehydration), a causal relationship cannot be excluded.   This case was linked to MOD-2021-108431 (Patient Link).; Sender's Comments: Based on the current available information and temporal association between the use of the product and the start date of the events (hypophagia, headache, hypersomnia and dehydration), a causal relationship cannot be excluded.