A vaccine reaction is any injury or condition that occurs as a result of a vaccination that has been given to protect against disease. Serious reactions to vaccines are very rare, and vaccination is far less risky than the catching the disease it prevents. Reference from A.D.A.M.
The United States Marine Corps (USMC), also known as the United States Marines, is a branch of the United States Armed Forces responsible for providing power projection, using the mobility of the United States Navy, by Congressional mandate, to deliver rapidly, combined-arms task forces on land, at sea, and in the air.
The U.S. Marines rely on the Navy for their field medical officers, called hospital corpsmen. Navy corpsmen have a variety of duty options, including attaching to a Marine field unit to offer medical support during operations and battle. A corpsman interested in working with Marines must undergo special training and be willing to fight alongside the Marines.