But knowing how much natural immunity has been acquired through infection is more difficult, especially given the very mild nature of illness in the vast majority of patients.

但很难说清因感染获得了何种程度的天然免疫力，尤其是因为在绝大多数患者身上，疾病的性质非常温和。

youdao

But knowing how much natural immunity has been acquired through infection is more difficult, especially given the very mild nature of illness in the vast majority of patients.

但很难说清因感染获得了何种程度的天然免疫力，尤其是因为在绝大多数患者身上，疾病的性质非常温和。

youdao