London, Nov 14 The virus responsible for causing common cold may help fend off common cold, reveals a new study.

In the study, researchers found that that the percentage of throat swabs from French respiratory illnesses that tested positive for swine flu fell in September, while at the same time rhinovirus, which causes colds, rose.

Jean-Sebastien Casalegno of the French national flu lab at the University of Lyon said that in late October, rhinovirus fell - at the same time as flu rose.

He believes rhinovirus may have blocked the spread of swine flu via a process called viral interference.

"We think that when you get one infection, it turns on your antiviral defences, and excludes the other viruses," New Scientist quoted Ab Osterhaus at the University of Rotterdam in the Netherlands as saying.

However, process of interference is unclear, as there have been cases where there is no interference, and people catch two viruses at the same time.

In another study, Mia Brytting of the Swedish Institute for Infectious Disease Control in Solna reported a rise in rhinovirus coupled with a decrease in swine flu. (ANI)