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By Linda Carroll

If you're worried about catching a cold, there's a simple act that may protect you against the virus and help you feel better right away: hug someone. 

Hugging can help prevent a cold virus or lessen symptoms in people who are already sick, according to a recent study published in Psychological Science.

We're told to avoid sweaty, germy handshakes during cold and flu season, but the warm embrace of a close friend or loved one may actually improve immune system functioning, says Sheldon Cohen, a professor of psychology at Carnegie Mellon University and lead author of the study.

The warm embrace of a close friend or loved one may actually improve immune system functioning. Blend Images / Today

Stress lowers the body’s defenses against viruses and other pathogens, research has shown. 

For the new study, Cohen and his colleagues rounded up 404 healthy adult volunteers, who were asked to fill out questionnaires to determine, among other things, whether and how often they’d been hugged during a two-week period and whether they’d experienced conflict or tension. Then the participants were deliberately exposed to the cold virus and immediately moved to quarantine for a week, while researchers monitored them for signs of infection and illness.  

People who were stressed —but got hugs —were less likely to become infected with the virus. Hugs made no difference among those who weren't stressed in terms of developing an infection.

Those who did develop an infection with the virus were less likely to feel sick if they'd been hugged in the prior two-week period. The more days someone was hugged, the lower the risk of infection (among those who were stressed). Similarly, the more days someone was hugged, the less likely they would experience cold symptoms when infected with the virus. 

Somehow, Cohen says, the social support signified by the hug seems to keep us from getting sick even when we’re infected.

Cohen says the findings don't mean you should be hugging sick people. His volunteers went into quarantine as soon as they were exposed to the virus. It’s the hugs people get when they are healthy that make the difference, he says.

The new findings aren’t a surprise to Dr. Nina Shapiro, director of pediatric otolaryngology at the Mattel Children’s Hospital at the University of California, Los Angeles, and a professor of head and neck surgery at the David Geffen School of Medicine at UCLA.

Shapiro has studied the mind-body connection in children who are getting surgery. If kids are given a sense of control over their destinies, they experience better outcomes and less pain after their operations, she says.

Beyond that, she says, “there are studies in cancer patients that show that they have better outcomes if they are emotionally supported.”

Still, Shapiro says, during cold season people should still be careful about exposure.

“Maybe we should say, ‘hug, but don’t kiss,’” she says.

Linda Carroll is a regular contributor to NBCNews.com and TODAY.com. She is co-author of "The Concussion Crisis: Anatomy of a Silent Epidemic” and the recently published “Duel for the Crown: Affirmed, Alydar, and Racing’s Greatest Rivalry”