>The flu virus is a very special case due to its rapid mutation and seasonal activity, which is the main reason why it's a challenge. Exactly. The flu and the

>The flu virus is a very special case due to its rapid mutation and seasonal activity, which is the main reason why it's a challenge. Exactly. The flu and the common cold viruses are different from most others, which is why we don't have a cold vaccine and our flu vaccine is only good for that season's flu (maybe). The flu and cold mutate very rapidly and constantly, whereas those other viruses don't.