Are you still susceptible to swine flu when you have had the injection for swine flu?

Maybe. All influenza vaccines (swine flu or seasonal) are most effective at reducing the degree of illness (how sick you get) from flu. The vaccines reduce spread of the virus from person to person, help avoid staying home from work, avoid hospitalization & reduce flu deaths. If you get flu, most likely the vaccine helped to reduce the severity of your illness & prevented spread of your flu to loved ones.