It isn't the virus that is the problem. What makes it more dangerous is the results of our immune system reacting to the virus. In Mexico those who died are in their 20's and 30's, the people with the strongest immune systems. The lungs fill up with inflammatory cells from fighting the infection so for once the weaker your immune system the better. Tamiflu works on this virus, however, so if you get it take Tamiflu and it will stop it from getting worse and even get you better. One of the first signs that you have it and are really sick is shortness of breath.