Between 2000 and 2015, new cases among populations at risk fell by 29 percent globally.

2000-2015年间，全球高危人群的比例下降了29%。

Dengue affects some 129 countries, with roughly half the world's population at risk, says the WHO.

世界卫生组织说，登革热影响着大约129个国家，世界上大约一半的人口处于危险之中。

Scientists say climate change could put their population at risk, so they are studying the whales to monitor changes.

科学家们说，气候变化可能会危及座头鲸的数量，因此他们通过对鲸鱼展开研究来监测变化。

And what started out as a way to save money in the struggling city has put parts of the population at risks.

事件的起因是为了给这个正陷入困境的城市节省金钱，但却因此对部分人的生命造成威胁。

The ideal way for testing a new drug would be to vaccinate half of a population at risk of contracting Ebola.

测试新药的理想方法是为一半有感染埃博拉病毒风险的人群接种疫苗。

Sometimes, epidemiologists are pretty on the nose when it comes to naming things, so the population at risk during an outbreak is called... The Population at Risk.

有时，流行病学家在命名事物时非常准确，所以在疾病爆发期间处于危险中的人群被称为——高危人群。

A vaccine trial in Equatorial Guinea could also provide valuable data on the safety of vaccines and the immune response they generate in populations at risk of future outbreaks.

在赤道几内亚进行的疫苗试验还可以提供有价值的数据， 说明疫苗的安全性以及它们在未来可能在爆发疫情的人群中产生的免疫反应。

And even though Tonga has a pretty high vaccination rate, letting international aid workers in could put their population at risk, and officials are just not willing to do that.

尽管汤加的疫苗接种率相当高，但让国际援助人员进入可能会把他们的人口置于危险之中，而官员们是不愿意这样做的。