Show Details

Symptomless Colds

July 18, 2012

You can spread the common cold even if you feel no symptoms.



Healthy, but contagious…I’m Bob Hirshon and this is Science Update.

Many people who are infected with a virus that causes the common cold never feel any symptoms. This according to researchers at McMaster University, who measured rhinovirus levels in students with and without cold symptoms. Epidemiologist Andrea Granados led the study.

ANDREA GRANADOS (McMaster University):

There was a 4-to-1 ratio of asymptomatic students to symptomatic students in an 8 week study period.


This means many people were contagious without knowing it. Granados says they unwittingly spread the virus through the air or by touching objects that other people touch.


My general message would be that asymptomatic infections are quite common and you want to be washing your hands frequently anytime you’re in contact with individuals or touching random things. You want to be sure to not touch your face that often because that’s how you transmit the virus to yourself.


I’m Bob Hirshon, for AAAS, the science society.

A McMaster University student being recruited for a study of seasonal viruses. (Marek Smieja)