Syncope; Right arm went completely numb; small pericardial effusion; Her right arm lost function and went completely flaccid; she could not move it; tingling; soreness was in her muscle where the injection was; muscle pain; soreness in right arm; D dimer: Elevated to 1.14; This is a spontaneous report from a contactable Other Health Professional (patient). A 36-year-old female patient received first dose of BNT162B2 (PFIZER-BIONTECH COVID-19 VACCINE, Solution for injection, Lot Number: EW0191), intramuscular, administered in Deltoid Right on 25Jun2021 15:00 (at age of 36 years old) as single dose for COVID-19 immunisation. Medical history included Rheumatoid arthritis from 2006 ongoing (She was diagnosed at 21. 15 years before 2021. She thinks 2006), compromised immune status, Family Medical History Relevant to AE(s): Mother has a history of stoke. She is only saying that because she had thought she herself had a TIA. That is why she went in because her arm was so numb. Her arm was numb Sunday through Monday. So she thought she better go and get it checked out. Fortunately there was no PE or evidence of stroke or anything. With her mom's medical history she thought she should get it checked out. The patient's concomitant medications were not reported. Prior Vaccinations (within 4 weeks) No, but she had a varicella booster on 21May2021 (at 36 years old). She had to put off her vaccine to make sure she waited the full month before the Pfizer vaccine. No AEs following prior vaccinations. Caller is calling regarding the COVID vaccine. She is reporting an adverse reaction to the first shot which she had on Friday at 3pm. Caller had to go to emergency department last night. She has a small pericardial effusion on 29Jun2021. It was very bizarre. She has never had any kind of adverse reaction to a vaccine before. She is calling because she feels like Pfizer needs to know. After she received the shot everything was fine, she just had soreness in her arm, no big deal. Then Sunday (27Jun2021) she had a syncope event where she almost lost consciousness and simultaneously her right arm went completely numb. Her right arm lost function and went completely flaccid. She had no voluntary control over her right arm. It went completely numb and she could not move it. soreness in right arm: Arm was very sore probably Friday (25Jun2021) and Saturday morning. She took some Ibuprofen and it was completely fine. She no longer felt pain by Saturday (26Jun2021) night. She no longer was feeling any kind of muscle pain from the injection. Caller clarifies that the soreness was in her muscle where the injection was. The muscle pain and soreness are the same thing caller further clarifies. It wasn't anything. It happened. The pericardial effusion was actually last night. It is probably the last one in the order of events. She states she found that out yesterday, actually early this morning. Probably 2am since she was in the Emergency Department forever. This is probably something that will need follow up with an echocardiogram and monitoring and possible medication. It's ok right now but if fluid keeps accumulating it can be lethal and would require a surgery to take the fluid off of the heart. Pericardial effusion is a small amount of fluid that builds up around the heart. The sack that holds your heart muscle, it builds up in-between there. She went to the hospital because of the adverse reactions she was having with the syncope and the numbness in the arm and that is what they discovered. The small pericardial effusion is what her scan found. Caller clarifies that she was not admitted to the hospital. Caller states that the fact that the syncope and numbness in her arm happened together is medically significant. If these things happen on their own it is one thing, but if they happen together that is medically significant that they happen simultaneously. They are less significant on their own than if they happened together. The right arm numbness did not resolve with the syncope. She regained function of her arm but she had numbness and tingling until yesterday. Today it feels much better. Caller states she wanted the Pfizer because that was her pick between that and Moderna. She preferred the Pfizer. She researched about it. She is just sad that she had an adverse reaction. She hopes no one else is having that, that is why she wanted to call to inform Pfizer. Reporter seriousness for Right arm went completely numb: Medically significant. The patient was hospitalized for Syncope and Right arm went completely numb on unknown date. The patient underwent lab tests and procedures which included D dimer: Elevated to 1.14 in 2021, scan: pericardial effusion on 29Jun2021. AE (except D dimer: Elevated) require a visit to Emergency Room. The outcome of the event Syncope was recovered on 27Jun2021, for Numbness of upper arm, Tingling was recovered on 28Jun2021, for Pericardial effusion was not recovered, for Pain in arm, Vaccination site pain, muscle pain was recovered on 26Jun2021, for other events was unknown. Relatedness of drug to reactions/events: For soreness in right arm was Related, for small pericardial effusion was Unknown, for Syncope was Related, for Right arm went completely numb was Related.; Sender's Comments: Based on the available information in the case, a possible contributory role of the suspect BNT162B2 cannot be excluded for the reported events syncope ,hypoaesthesia and pericardial effusion.  The impact of this report on the benefit/risk profile of the Pfizer product is evaluated as part of Pfizer procedures for safety evaluation, including the review and analysis of aggregate data for adverse events. Any safety concern identified as part of this review, as well as any appropriate action in response, will be promptly notified to regulatory authorities, Ethics Committees, and Investigators, as appropriate.