How many times can a person get Swine Flu?

Answer 1

You can only get the same exact strain one time, but sometimes they mutate enough that your body no longer recognizes them as the same virus you had and then your prior immune response won't protect you from the new version until you are vaccinated or exposed again to the new mutated virus.

Other times the mutations are not big enough changes to make them unrecognizable though, and so our immune systems do know how to attack and inactivate them.

For now, the strain of Swine Flu that caused the pandemic has not mutated to significantly different strains, and so the vaccine this year for it is the same as the strain in the vaccine last year. It is included in the trivalent seasonal flu vaccine for 2010-2011 flu season in the US. If you got the vaccination last year, you should still get the seasonal flu shot, because it also contains the other two likely to be spreading types of flu. It won't hurt to get a second dose of the H1N1/09 vaccine in any way, so just in case you had a different flu and not the pandemic swine flu before (you can't be sure unless you had specific lab tests to confirm the specific type), you will be best protected by getting the trivalent vaccine this year (trivalent just means it contains vaccine for three flu viruses).