HEART RATE IN THE 50'S; PAIN IN STERNUM/ ENTIRE CHEST HURTS; PRESSURE ON THE RIGHT SIDE OF CHEST; HEART PALPITATIONS/SENSATION OF HEART TUMBLING; PAIN IN ARM DURING INJECTION DUE TO VACCINE BEING COLD; This spontaneous report received from a patient concerned a female of unspecified age. The patient's height, and weight were not reported. The patient's past medical history included: anemia, and concurrent conditions included: weak immune system, hay fever allergy, and allergies to cat, dogs, dustmite. The patient had no allergies to any medications. The patient used inhalers in her 30s for four to five years. The patient was hospitalized for anemia when 2 years old and again at 4 years for anemia. The patient received covid-19 vaccine ad26.cov2.s (suspension for injection, route of admin not reported, batch number: Unknown) dose was not reported, 1 total administered on 28-JUL-2021 for prophylactic vaccination. The batch number was not reported. The company was unable to perform follow up to request batch/lot numbers. No concomitant medications were reported.  On 28-JUL-2021, the patient experienced pain in arm during injection due to vaccine being cold. The patient felt pain in sternum, pressure on the right side of chest, heart palpitations and heart tumbling. On 29- JUL-2021 patient had talked with the nurse and instructed to go to emergency room. On 30-JUL-2021, the patient went to emergency room because the pain was not getting better and the heart rate was in 50's. The patient had undergone blood test, lung X-ray, heart scan, electrocardiogram(EKG) for which results were not reported and oxygen saturation was 98%. The patient's physician stated that at that moment patient was fine, but if experienced again or long term need to come back and later patient was discharged. The patient was hospitalized for 1 day and was discharged on 30-JUL-2021. On 04-AUG-2021, the patient again contacted the nurse and the nurse clarified everything about the symptoms. The heart rate went back to 60's. The pain was much better. On 05-AUG-2021, the patient's pain got better to 1 and 2 instead of 4 or 5. On 06-AUG-2021 patient reported that heart rate was never in 50's only in upper middle 60's. She reported helping with a move then her heart rate went back into the 50's and upper 60's and reported entire chest hurts.  The action taken with covid-19 vaccine ad26.cov2.s was not applicable. The patient had not recovered from pain in sternum/ entire chest hurts, and heart rate in the 50's, and the outcome of pain in arm during injection due to vaccine being cold, pressure on the right side of chest and heart palpitations/sensation of heart tumbling was not reported. This report was serious (Hospitalization Caused / Prolonged).; Sender's Comments: V0- 20210815139-Covid-19 vaccine ad26.cov2.s- Heart rate in the 50's, pain in sternum/ entire chest hurts,pressure on the right side of chest and heart palpitations/sensation of heart tumbling. This event(s) is considered unassessable. The event(s) has an compatible/suggestive temporal relationship, is unlabeled, and has unknown scientific plausibility. There is no information on any other factors potentially associated with the event(s). 20210815139-Covid-19 vaccine ad26.cov2.s-Pain in arm during injection due to vaccine being cold. This event(s) is labeled per Regulatory Authority and is therefore considered potentially related.