Another form of the enzyme creates a protective effect.

VOA: special.2009.10.20

It turns out that if you give one child in a home the oral vaccine, you often have a protective effect in other children in the home as well because it spreads from one individual to another.

结果显示,如果给一个家庭中的,一个孩子服用了口服疫苗,就等于给家中的其他孩子,同样进行了保护,因为它会在个体之间进行传播

耶鲁公开课 - 生物医学工程探索课程节选

"We saw a protective effect for drinking more than 4 cups of coffee per day."

VOA: standard.2010.06.30

Two years ago,European researchers reported that aspirin may have what they called a "long-term protective effect against colorectal cancer."

VOA: special.2010.12.14