Sensitization to severe dengue illness through pre-existing immunity is a serious safety concern for vaccination.

免疫接种时的一个严重的安全性问题是由于先前已经存在的免疫性而触发严重登革热。

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The H1N1 pandemic was characterized by the emergence of a new influenza virus to which many people had no pre-existing immunity.

H1N 1流感大流行的特点是出现新的流感病毒，而许多人对其并没有预先存在的免疫力。

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What we have found is that the swine flu has similarities to the seasonal flu, which appear to provide some level of pre-existing immunity.

我们发现的是，猪流感与季节性流感有相似之处，它可以提供某种之前存在的免疫性。

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But the current swine flu is a new strain to which humans have no immunity and against which existing vaccines offer no protection.

VOA: standard.2009.04.30

CISPA, which passed the House last year but never reached a vote in the Senate, has drawn fire for a provision that would allow companies to hand over cybersecurity threat information to government agencies that include the National Security Agency and Department of Defense, even granting them immunity from existing laws and regulations that would prevent the sharing of some sensitive information.

FORBES: President Obama's Cybersecurity Executive Order Scores Much Better Than CISPA On Privacy

UN's secretary-general, Kofi Annan, affirming Mr Cumaraswamy's role and his immunity from prosecution under existing conventions.

ECONOMIST: Malaysia��s rough justice

The current recommendation is based on unique conditions associated with the existing pandemic, including low levels of population immunity to 2009 H1N1, the potential for health-care personnel to be exposed to H1N1 patients, and other factors, Dimond says.

CNN: STORY HIGHLIGHTS