About one in four people who get the vaccine have mild problems up to 10 days after the shot. They include fever, body aches and soreness, redness or swelling where the shot was given. In rare cases, the shot causes severe allergic reactions that are sometimes fatal. One in every 131,000 people has serious allergic symptoms. One person in every 150,000 to 250,000 who gets a shot has serious reactions that affect the nervous system. About one out of every 200,000 to 300,000 people has a severe illness with major organ system failure. These reactions are more common in those 60 and older, which is about one in 40,000 to 50,000. Symptoms of a severe reaction include: rash, hives, itching, difficulty breathing, tightness in the chest and swelling of the mouth, face, lips or tongue. For severe reactions, seek medical attention immediately or call 911.