The vaccine generally takes effect about two weeks after immunization, and protection may last six months or longer. October or November are the best times to be vaccinated. Your doctor or a medical clinic can provide a vaccination. Influenza vaccination cannot cause influenza because the vaccine does not contain live virus. Minor soreness at the injection site lasting up to two days is common.
Allergic reactions are rare.
Flu vaccine contains a minute amount of egg protein, which may cause an adverse reaction in some people. If in doubt, check with your doctor. The Division of Respiratory Diseases handles issues related to pathogens of the respiratory tract, including influenza viruses.