If H1N1 mutates, then it will no longer be H1N1, it will be identified as a different strain. So a second pass would only affect those who were not already exposed on the first pass and had their God given immune system build a perfect defense. If you are someone withe HIV, AIDS, Lupus or some other immune defiency disorder, I wouldn't worry too much. If you do get it, drink plenty of fluids, (orange juice is not the greatest as mom said, the sugars inhibit immune funcyion at a greater extent than the benifit of the vitamin C), take Esberitox, zinc, and Cellylar Forte'. These will be great starters and cut the sick time in half. If it were H5N1, then I would worry, that has a 60% mortality rate, H1N1, no big deal. That second pass stuff is scare tactics, and I just had it confirmed by my immunology professor from grad school.