No @quiplet. Immunity is the term we use to just describe about the our body's self fighting mechanism against the pathogens. It's not a trouble. It's a mechanism that has evolved over millions of years. Those unlucky humans or other organisms who were not having good immunity could not pass there Gene to their subsequent generations. So those who are surviving now are the offsprings of those who have good immunity. That's why we have good immunity. But the story is not over. Every humans are born with about 60 - 70 mutations. One or several of those may make them again vulnerable to certain disease. So they become the next unlucky individuals. Mutations are happening for pathogens also. Some of them, enabling to attack as more efficiently and some less efficiently. More efficient pathogens will increase over time. The story continues .......