Tachycardia; Started feeling weird/felt awful/She continues to have brain fog; Feeling not well; Ringing in the ears/tinnitus; Stiffened neck; Eyes watery and still are; She could not sleep the first night/slept fitfully; Rapid heart bit for a while (less than an hour)/heart racing; Felt like her head was filled with cement or concrete; Shaking/ intermittent shakes; Body aches/aches and pains all over; Fever/Elevated temperature; Knees: ache and pain; Where she got the vaccine it was red; Headache; Where she got the vaccine it was swollen; Extreme fatigue; Chills; This spontaneous case was reported by a nurse and describes the occurrence of FEELING ABNORMAL (Started feeling weird/felt awful/She continues to have brain fog), MALAISE (Feeling not well), TINNITUS (Ringing in the ears/tinnitus), MUSCULOSKELETAL STIFFNESS (Stiffened neck) and LACRIMATION INCREASED (Eyes watery and still are) in a 78-year-old female patient who received mRNA-1273 (Moderna COVID-19 Vaccine) (batch nos. 017F21A, 026A21A and 010M20A) for COVID-19 vaccination. The occurrence of additional non-serious events is detailed below.     No Medical History information was reported.   On 04-Mar-2021, the patient received first dose of mRNA-1273 (Moderna COVID-19 Vaccine) (Intramuscular) 1 dosage form. On 08-Apr-2021, received second dose of mRNA-1273 (Moderna COVID-19 Vaccine) (Intramuscular) dosage was changed to 1 dosage form. On 04-Nov-2021, received third dose of mRNA-1273 (Moderna COVID-19 Vaccine) (Intramuscular) dosage was changed to 1 dosage form. On 04-Nov-2021, the patient experienced FEELING ABNORMAL (Started feeling weird/felt awful/She continues to have brain fog), MALAISE (Feeling not well), TINNITUS (Ringing in the ears/tinnitus), MUSCULOSKELETAL STIFFNESS (Stiffened neck), LACRIMATION INCREASED (Eyes watery and still are), INSOMNIA (She could not sleep the first night/slept fitfully), PALPITATIONS (Rapid heart bit for a while (less than an hour)/heart racing), HEAD DISCOMFORT (Felt like her head was filled with cement or concrete), TREMOR (Shaking/ intermittent shakes), MYALGIA (Body aches/aches and pains all over), PYREXIA (Fever/Elevated temperature), ARTHRALGIA (Knees: ache and pain), VACCINATION SITE ERYTHEMA (Where she got the vaccine it was red), HEADACHE (Headache), VACCINATION SITE SWELLING (Where she got the vaccine it was swollen), FATIGUE (Extreme fatigue) and CHILLS (Chills). On an unknown date, the patient experienced TACHYCARDIA (Tachycardia). The patient was treated with PARACETAMOL (TYLENOL [PARACETAMOL]) for Adverse event, at a dose of 3 times. At the time of the report, FEELING ABNORMAL (Started feeling weird/felt awful/She continues to have brain fog), TREMOR (Shaking/ intermittent shakes), HEADACHE (Headache) and CHILLS (Chills) had not resolved, MALAISE (Feeling not well), TINNITUS (Ringing in the ears/tinnitus), MUSCULOSKELETAL STIFFNESS (Stiffened neck), LACRIMATION INCREASED (Eyes watery and still are), INSOMNIA (She could not sleep the first night/slept fitfully), HEAD DISCOMFORT (Felt like her head was filled with cement or concrete), MYALGIA (Body aches/aches and pains all over), PYREXIA (Fever/Elevated temperature), ARTHRALGIA (Knees: ache and pain), VACCINATION SITE ERYTHEMA (Where she got the vaccine it was red), VACCINATION SITE SWELLING (Where she got the vaccine it was swollen), FATIGUE (Extreme fatigue) and TACHYCARDIA (Tachycardia) outcome was unknown and PALPITATIONS (Rapid heart bit for a while (less than an hour)/heart racing) had resolved.      DIAGNOSTIC RESULTS (normal ranges are provided in parenthesis if available): On 04-Nov-2021, Body temperature: elevated (High) Elevated. On 04-Nov-2021, Heart rate: rapid (High) Rapid heart bit for a while (less than an hour).     For mRNA-1273 (Moderna COVID-19 Vaccine) (Intramuscular), the reporter did not provide any causality assessments.   The patient had first and second of Moderna and did not had side effects. Some symptoms started around midnight and many resolved the next day. Patient had not discussed her symptoms with her HCP.  This spontaneous case concerns a 78-year-old female patient with no relevant medical history reported, who experienced non-serious unexpected event of special interest (AESI) tachycardia. The event occurred on the evening after receiving the third, booster dose of the Moderna COVID-19 Vaccine (mRNA-1273). The event, in addition to other symptoms, occurred in the midnight and majority of symptoms resolved the next day. Rechallenge was not applicable since the event occurred after the third dose so, no rechallenge was done and recurrence was not applicable.  The benefit-risk relationship of drug is not affected by this report.   Most recent FOLLOW-UP information incorporated above includes: On 09-Nov-2021: Added vaccine information for all the doses, added events chills, pyrexia, Head discomformt and added start date for all the events and updated outcome for feeling abnormal, headache shaking.; Sender's Comments: This spontaneous case concerns a 78-year-old female patient with no relevant medical history reported, who experienced non-serious unexpected event of special interest (AESI) tachycardia. The event occurred on the evening after receiving the third, booster dose of the Moderna COVID-19 Vaccine (mRNA-1273). The event, in addition to other symptoms, occurred in the midnight and majority of symptoms resolved the next day. Rechallenge was not applicable since the event occurred after the third dose so, no rechallenge was done and recurrence was not applicable.  The benefit-risk relationship of drug is not affected by this report.