Colds and the Flu - Risk Factors

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Traveling in Trains, Buses, and Planes

Traveling in close contact with people, whether on trains, planes, or buses, can increase the risk for respiratory infections. (A 2002 study suggested that the risk for a cold was about 20% after flying.) There has been particular concern that aircraft air that is recirculated can increase the risk for such infections. The same 2002 study, however, reported no difference in colds and flus among those who traveled in planes with fresh air versus recirculated air.

Day Care Centers

Children who attend day care may have an increased risk of colds. However, a 2002 study suggested that although children in day care centers incur higher rates of the common cold in the preschool years, they have lower cold rates in their first years of regular school. The colds they catch in day care, then, may bestow some immunity to future colds for a few years. By age 13, such protection has worn off. There is also some evidence that frequent colds in young children may help protect against future allergies and asthma.

Review Date: 03/06/2007
Reviewed By: A.D.A.M. Editorial Team: Greg Juhn, M.T.P.W., David R. Eltz, Kelli A. Stacy. Previously reviewed by Harvey Simon, MD, Associate Professor of Medicine, Harvard Medical School; Physician, Massachusetts General Hospital (12/4/2006).

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