India, Jan. 13 -- Researchers from the University of Maryland explored how the flu spreads. To study this, they placed college students who already had the flu in a hotel room with healthy, middle-aged adult volunteers.

The study, published in PLOS Pathogens, is the first controlled clinical trial to closely study how the flu spreads through the air from people who were naturally infected, not deliberately infected in a lab, to people who were healthy.

At the end of the study, even though the infected students had high levels of the flu virus in their noses, they did not cough very often. Because of this, only small amounts of the virus were released into the air.

"Being up close, face-to-face with other people indoors where the air is...