A child once infected with the measles is safe from having it a second time.

曾经患过麻疹的孩子不会有再患的危险。

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On the other hand, once infected with HIV, the human immune cells will attack and human histocompatibility antigen-binding HIV.

另一方面，一旦感染了艾滋病病毒，人的免疫细胞就会攻击与人组织相容性抗原结合的艾滋病病毒。

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We can also say that once most people have been infected by swine flu and become immune, a variant that can beat that immunity will replace the current strain.

我们还可以确定的是，一旦大部分人群感染猪流感并获得免疫力，疾病的变种将会打破目前的免疫性并成为当下的压力。

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People think that once you get infected one time you develop immunity for the rest of your life.

VOA: special.2011.04.20

Once infected, a computer becomes connected to a botnet that is still active today.

FORBES: Anti-Mining Group In Vietnam Hit With Botnet-Building Malware

Once infected, a person is immune from further infection for life.

BBC: Infection risk posed by cats revealed

Once infected, there is no cure, but if discovered, the disease can be managed, and the risk of cancer or other complications can be significantly reduced.

WHITEHOUSE: Hepatitis B and the AAPI Community