If I was vaccinated am I immune to the disease if people around me have it?

If you have been vaccinated against mumps you are most likely immune. there are not multiple strains of mumps like with the flu. If your immune system is weakened then you might still be at risk or if your vaccination did not "take", there is a blood test called an antibody titer test that could tell you for sure. as far as the H1N1, it is not known if you will get 100% immunity remember at first they were talking about two shots? however, you are definitely better off getting the vaccine, it takes about two weeks to develop full immunity longer depending on your health so you have a window but even if you get infected it is likely to be a less severe infection because your body was at least partially ready for it.