the teeth chattering only occurs when she puts her teeth together, its like she is freezing; chin trembling/chin is jumping up and down; This is a spontaneous report from a contactable consumer. This consumer reported for a 84-year-old female patient (sister) that:  Patient characteristics: Age at time of onset of reaction/event: 84 Age at time of onset of reaction/event (Unit): Year Weight (kg): 61.23  Reaction(s)/Event(s): Reaction/event as reported by primary source: Teeth chattering  Reaction/event in MedDRA terminology (LLT): Teeth chattering Reaction/event MedDRA term (PT): Chills Date of start of reaction/event: 03Feb2021 Outcome of reaction/event at the time of last observation: NOT RECOVERED/NOT RESOLVED  Drug(s) Information:  Characterization of drug role: (SUSPECT) Proprietary medicinal product name: COVID-19 Vaccine    Batch/lot number: Unknown Dosage text: first dose, intramuscular injection    Date of start of drug: 02Feb2021 Action(s) taken with drug: Unknown  Narrative case summary and further information: Case narrative: Selected Report Type: Initial Is the patient also the reporter? No Reporter type: Consumer or other non health professional  Primary / Prescribing Healthcare Professional Info Dates for Teeth chattering: (From: 03Feb2021 To: Ongoing)  Is COVID-19 Vaccine a Pfizer product? Unspecified COVID-19 Vaccine manufacturer: Unspecified Dates for COVID-19 Vaccine: (Start: 02Feb2021 Stop: Unspecified) NDC number of COVID-19 Vaccine: Unknown Reason for no lot number: of COVID-19 Vaccine: Other: Caller does not have her sister's vaccine record card Expiry Date of COVID-19 Vaccine: Unknown  Other Products: No Patient History: No Investigation Assessment: No  Additional Context: Caller states she is calling on behalf of her sister, (Name). They received the first shot of the Pfizer COVID-19 Vaccine. The caller states they were all doing really well except her sister woke up and when she puts her teeth together, her teeth are chattering. Her chin trembles really fast. Caller wants to know have there been any other reports of this occurring?  Height: 5'6'' or 5'7''  Caller declined to include a healthcare professional.  Caller states the teeth chattering only occurs when she puts her teeth together, its like she is freezing. Her chin is jumping up and down.   VACCINE SUPPLEMENTAL FORM Patient Details- Last name: (Last name) First: (First name) Address: (Address) (City name), (State name) (Postal Code) Telephone number: doesn't have one Pfizer Suspect Vaccine and Vaccination Details Vaccine Lot Number:  Unknown  Vaccine Lot Expire Date: Unknown Time the Vaccination Was Given: 12:30pm  Anatomical Location of Administration of Pfizer vaccine considered as suspect: Left arm  Vaccination Facility Type: (Vaccination Facility Name) in (Vaccination Facility City), (Vaccination Facility State)  For US Only: Vaccine Administered at Military Facility? No  Vaccination Facility Address: Unknown, she knows its on (Vaccination Facility Address) in (Vaccination Facility City), (Vaccination Facility State).   History of all previous immunization with the Pfizer vaccine considered as suspect (or patient age at first and subsequent immunizations if dates of birth or immunizations are not available); n/a; this was the patient's first dose  Additional Vaccines Administered on Same Date of the Pfizer Suspect: None  Adverse Event (AE) Details: Teeth chattering/chin trembling Time of onset: about 8am    Additional Information Did any AE(s) require a visit to: Emergency Room?  No Physician Office? No   Prior Vaccinations (within 4 weeks): None  AE(s) following prior vaccinations Patient's Medical History (including any illness at time of vaccination): None  Relevant Tests: None  Information on the Lot/batch number has been requested.  Follow-up (16Apr2021): This follow-up is being submitted to notify that the lot/batch number is not available despite the follow-up attempts made. Follow-up attempts have been completed and no further information is expected.