Overall infection rate is low, but high among people in their 20s-the most economically productive age group.

总体感染率较低，但在20多岁这一最具经济活力年龄组别人群中的感染率较高。

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It is the sort of bulge in the numbers of people in productive age groups that produced explosive growth in China and South-East Asia.

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Workers are now at their most productive age, he said.

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Between 2m and 3m of the country's 40m people are thought to be infected and most new carriers are in the most economically productive age-group of 15 to 40.

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