A vaccine, like any medicine, is capable of causing serious problems, such as severe allergic reactions. The risk of any vaccine causing serious harm, or death, is extremely small. Local symptoms may include: sight tenderness redness, itching or swelling at the site of injection. Systemic symptoms may include: fever, malaise and muscle pan. Other systemic symptoms may occur infrequently. These reactions usualy begin 6 to 12 hours after immunization and can persist for a few days. Immediate presumable allergic reactions such as hives, angioedema, allergic asthma or systemic anaphylaxis occur rarely after immunizations. These reactions may result from from hypersensitivity reactions in people with severe egg allergy, and such people should not be given certain vaccines that contain eggs. People with documented immunoglobulin E (IgE)-mediated hypersensitivities to eggs or other vaccine components, including thimerosal, may also be at increased risk of reactions from inmunizations. In the case of a severe reaction such as high fever, behavior changes or fu like symptoms that occur after vaccination, see a doctor right away. Signs of an allergic reaction can indude dificulty breathing hoarseness or wheezing hives, paleness, weakness a fast heartbeat, or dizziness within a few minutes to few hours after the shot.