While simpler viruses such as the flu simply mutate their outer coats to evade the human immune system, HSV and other persistent viral infections are much more stable.

• 虽然简单的病毒如流感病毒仅靠外壳突变就可以侵入人类免疫系统，但是（与之相比），HSV和其它持续性感染的病毒要稳定的多。