News Plus慢速英语:美科学家招志愿者喷活体病毒 研发流感疫苗

This is NEWS Plus Special English. I'm Marc Cavigli in Beijing.
Forget being sneezed on: U.S. scientists are deliberately giving dozens of volunteers flu by squirting the live virus straight up their noses.
It may sound bizarre, but the rare type of research is a step in the quest for better flu vaccines. It turns out that how the body fends off influenza remains something of a mystery.
Doctor Matthew Memoli of the U.S. National Institutes of Health says vaccines are working, but people can do better.
Memoli is leading the study that aims to infect up to 100 adults over the next year.

Wait a minute: Flu is sweeping the country, so why don't just study the already sick?
That wouldn't let scientists measure how the immune system reacts through each step of infection, starting with that first exposure to the virus.
It's not an experiment to be taken lightly. After all, the flu kills thousands of Americans a year.
For safety, researchers chose a dose that produces mild to moderate symptoms; and they accept only volunteers who are healthy and no older than 50.
To avoid spreading the germs, participants must spend at least nine days quarantined inside a special isolation ward at the institute's hospital. Their health conditions are closely monitored.
The volunteers will not be released until nasal tests prove they're no longer contagious.