Vaccine-Related Shoulder Injury (SIRVA): This condition is characterized by shoulder pain and limited range of motion, occurring after receiving a vaccine, typically within 48 hours to 2 weeks. However, symptoms can sometimes persist or appear later, potentially radiating to the elbow due to referred pain or the involvement of the brachial plexus.

Brachial Neuritis: An inflammatory condition affecting the nerves of the arm, which can cause severe pain, often starting in the shoulder and potentially radiating down to the elbow. It can be idiopathic or post-infectious, including post-vaccination.
Tendinitis or Bursitis: Inflammation of the tendons or bursae around the elbow or shoulder, which could be exacerbated by the vaccine or coincidental, leading to pain that might shoot into the elbow.
Radial Neuropathy: Compression or injury to the radial nerve can cause pain, weakness, or numbness in the back of the hand or the thumb side of the hand, potentially radiating to the elbow.

Acute Coronary Syndrome or Myocardial Infarction: Although less common and not directly related to the vaccine, chest pain or discomfort that radiates to the arm (including the elbow) can be a sign of a heart attack. This is particularly important in individuals with risk factors for cardiovascular disease.
Deep Vein Thrombosis (DVT): A blood clot in the deep veins of the arm, which is a rare but serious condition that could potentially cause arm pain, including pain that might be perceived as shooting into the elbow.
Cervical Radiculopathy: Nerve root compression in the cervical spine can cause pain, numbness, or weakness in the arm, including the elbow, and is essential to diagnose due to its potential for serious neurological consequences if left untreated.

Complex Regional Pain Syndrome (CRPS): A chronic pain condition characterized by severe, burning pain at the site of an injury, which can sometimes be triggered by a vaccine. It's rare but can cause significant morbidity.
Vasculitis: Inflammation of the blood vessels, which can be caused by an autoimmune response potentially triggered by a vaccine, leading to a wide range of symptoms including pain in the arms.
Neoplastic Conditions: Although extremely rare, new onset of arm pain could, in some cases, be related to a tumor compressing nerves or invading bone or soft tissue, necessitating a thorough investigation if other diagnoses are ruled out.