Existing flu vaccines all work by mimicking natural infections .

现有的流感疫苗均通过模拟自然感染而起作用。

Can animal models predict protection provided by meningococcal vaccines ?

动物模型能够预测流脑菌苗的保护作用?

Because vaccines don 't always take .

因为疫苗并不总是起作用。

How are flu vaccines made ?

流感疫苗是怎么制备的？

Both the combined mmr vaccine and the single vaccines work well .

mmr联合疫苗和单一疫苗两者都有良好效果。