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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。

Breast milk reduces the risk of infections , chronic diseases and obesity .

母乳能减少得传染病、慢性病和肥胖症的风险。

She and her colleagues say a liquid that 's rubbed on the ears can prevent ear infections .

她和其他同事宣称，一种涂抹在耳朵上的药水能够预防耳炎。

Consistent and correct use of condoms is the most effective way for sexually active teens to protect themselves from sexually transmitted infections .

每次并正确使用避孕套对于性行为活跃的青少年来说是预防性传播疾病的最有效的方法。

Also talk with your doctor about other ways to protect yourself from sexually transmitted infections .

还要跟你的医生谈谈其它保护你免遭性传播传染病的方法。