Most existing vaccines elicit a targeted antibody response, but safely activating cellular immunity against many infectious diseases remains a challenging task.

多数现存疫苗所引发的是特定抗体反应，至于想要安全活化细胞免疫，来对抗许多传染病，目前还是一项挑战。

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The report estimates it will cost an additional $1 billion per year to ensure that new and existing vaccines will be delivered to all children in the 72 poorest countries.

据报告测算，每年将需要新增10亿美元成本，才能确保向72个最贫困国家的所有儿童提供新型和现有疫苗。

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Improved routine immunization: Partnerships focused on reducing diseases like polio and measles are also helping build a stronger foundation for the delivery of both new and existing vaccines.

改进的常规免疫：关注于减低诸如脊髓灰质炎和麻疹等疾病的合作也为新的和现有的疫苗交付提供一个更加坚实的基础。

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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

Existing vaccines work against viruses and bacteria, but the parasite that causes malaria is a more complex type of organism.

ECONOMIST: Malaria research gets a shot in the arm

Foot-and-mouth is endemic in central Africa, parts of the Middle East and Asia, so this would be a significant improvement over existing vaccines.

BBC: Synchrotron yields 'safer' vaccine

The technology, however, could be applied to other vaccines, such as those against influenza virus, or vaccines under development for TB and malaria or for existing vaccines administered in childhood.

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