If your arm is sore from the new crown booster shot, you can apply hot compresses locally, and if it continues to worsen, you need to seek immediate medical attention. If the symptoms of arm pain appear after receiving the new crown booster shot, it is generally an adverse reaction to the vaccine, which belongs to the normal range, no need to worry too much, you can use a hot towel to apply hot compresses to the local area, to promote local blood circulation, so as to restore the normal state more quickly. However, if the pain is not relieved or even aggravated after applying hot compresses and resting, then you must consult a doctor immediately for blood tests and local secretion cultures to determine whether there is any infection at the site of the vaccination, and if there is, then you need to treat the symptoms according to the doctor’s instructions.