NPR News: A box of 200 mosquitoes did the vaccinating in this malaria trial. That's not a joke!

A box of 200 mosquitoes did the vaccinating in this malaria trial. That's not a joke!
Volunteers for the trial put an arm over a box with hundreds of mosquitoes carrying a genetically modified malaria parasite. Here's why they did it that way — and why the trial holds promise.

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