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Why Some People Evade Colds And Others Don't

An airline passenger wears a mask to protect against viruses. Passengers are at risk of becoming infected in the airplane's cabin, just as they would be in any crowded, confined space. (AFP via Getty Images)

During a recent trip across the country, I got a severe cold that took me out of work for a week. My 85-year-old mother, on the other hand, remained healthy. I might have figured that, at her age, my mother was more fragile and therefore more susceptible to getting sick. I figured wrong.

It illustrates what many cold experts call the million-dollar question: Why do some people get sick and others in similar environments don't?

There's no cure or effective treatment for the common cold. Over-the-counter remedies may control symptoms, but they don't cure them.

While it's certainly true that our environment can increase our risk of infections, researchers suspect that much of our vulnerability has to do with our genes. For the cold virus itself, some of us humans are easier to infect than our more sturdy counterparts.

So, in infectious-disease labs across the country, researchers are trying to crack the genetic cold code and identify the exact mechanisms that enable cold viruses to make us sick as well as the specifics of how our innate immune systems respond — or don't respond — to the viral mechanisms that make some of us easier targets.

Building Immunity

Gregory Poland, director of Mayo Clinic's Vaccine Research Group and a professor of medicine and infectious diseases, says my mother's age was actually her "secret weapon." Poland says she's come face to face with many more viruses over the course of several decades than I. The virus that infected me on the airplane, he says, was likely one of these. Clearly, she has "some level of immunity" to that particular cold virus.

Once exposed, Poland says, most people have lifelong immunity — but only to that one particular cold virus. And, because there are hundreds of different cold viruses, there's also the matter of chance. Are you in the wrong place at the wrong time?

It seems I was. Because cold viruses are airborne, a cough or sneeze a few rows away could have blown millions of microscopic viruses my way. And if I had turned on my little overhead fan, I could have unknowingly blasted those viruses even faster toward me. All I needed to do after that was touch my eyes, nose or mouth and — voila! Infection.

Dangerous Liaison

On the other hand, the dangerous liaison could have occurred more surreptitiously. Poland says that perhaps I had gone to the bathroom, opening the door and touching the doorknob after a passenger with a cold did the same thing. Cold viruses, of course, also travel by contact and infect us via an object like a doorknob.

Take the example of any public gathering, Poland says. Say you're in a theater, auditorium or church. "Take your eyes off the speaker for a moment and look at the people around you," Poland says. "And what you'll find is that about every minute or two, people have their hand on their face, a number of them have their fingers in their nose, a number of them will cough or sneeze into their hand, and then what they'll do is turn and extend their hand to you."

This is an example of not practicing what Poland describes as "respiratory etiquette." He says it seems many adults have missed the message children get in school: Sneeze or cough into the crook of your elbow, not into the air and not into your hand.

All in all, Poland says it's the combination of genetics, immunity and exposure that determine whether you become sick with a cold.

Cure For The Common Cold

John Treanor, a vaccine expert at the University of Rochester, says it will be years before scientists know what really causes a cold.

"One great outcome of really understanding why some people get sick is to develop medicines or vaccines that target those mechanisms and effectively prevent respiratory illnesses or treat them," Treanor says.

And that would be a great leap in cold mechanics, especially when you consider that, according to Poland, the average person spends about one year of their life in bed, sick with a cold.

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Transcript

STEVE INSKEEP, host:

It's MORNING EDITION, from NPR News. Good morning. I'm Steve Inskeep.

RENEE MONTAGNE, host:

And I'm Renee Montagne.

In Your Health today, we consider the common cold and its frequent companion, the germ-spreading sneeze. At this time of year, cold germs are circulating just about everywhere. Those germs can make one person sick, while the next person suffers no ill effects.

NPR's Patti Neighmond went looking for an explanation.

PATTI NEIGHMOND: If you ask around, you'll probably find everybody's got a story like this. Here's mine. Recently, my mother and I flew across country. A few days later, I got a really bad cold. My 85-year-old mother didn't. I'm not the only one who'll tell you that it just seems unfair who gets colds and who doesn't.

My colleague Jane Greenhalgh got really sick last winter. So did her children. But not her husband Tom.

Ms. JANE GREENHALGH: If there's a cold going around, the kids get it. I get it. Tom never gets it. It's a bit irritating, actually.

NEIGHMOND: And studies show this kind of experience is really common. Dr. Greg Poland of the Mayo Clinic says his wife has never spent a day in bed.

Dr. GREG POLAND (Mayo Clinic): We'll be sick. You know, we'll be moaning and groaning, and I'll be sick in bed with a little bell to call her because I'm so weak and can't get up. And she's just never ill.

NEIGHMOND: Poland's a cold expert, and he told us genes have a lot to do with who gets sick.

Dr. POLAND: Jane, you're married to superman. And I got superwoman. I think what we're going to find as the years go by is that Tom has a set of genes that, together, basically form an immunologic barrier for him against many of these common viruses.

NEIGHMOND: But what about me and my mother on the airplane? I figured that at 85, she was more fragile and therefore more susceptible to getting sick. I figured wrong. As Dr. Poland says, her age was probably her secret weapon.

Dr. POLAND: Your mother, who's older than you, has undoubtedly seen many more of these sorts of respiratory viruses than you and may well have encountered that one sometime in her previous 70, 80 years, and hence has some level of immunity to it.

NEIGHMOND: Once exposed, most people have lifelong immunity, but only to that one particular virus. And there are hundreds of different cold viruses. And here's where total chance comes in. If you happen to be in the line of fire of even one sneeze or a cough, the cold viruses can get you.

Dr. POLAND: Millions. There's millions and millions of them.

NEIGHMOND: And if you're not already immune, like my mother probably was, and if you're sitting in a narrow airplane seat like I was, sharing an armrest with your neighbor, you're even more at risk, because cold viruses not only travel through the air, they travel when you touch another person or even an object.

Dr. POLAND: Maybe I get up to go to the bathroom and you didn't, but the guy who went to the bathroom right before me has a cold, sneezed into his hand, grabbed the doorknob. And then I come right behind him and grab it.

NEIGHMOND: So a combination of genetics, immunity and exposure all determine whether or not we get sick. And sometimes we make it really easy for cold germs to get us. Take public gatherings, for example, like theater or church.

Dr. POLAND: Take your eyes off the speaker for a moment and look at the people around you. What you'll find is that about every minute or two, people have their hand on their face, a number of them have their fingers in their nose, a number of them will sneeze or cough into their hand. And then what they'll do is turn and extend their hand to you.

NEIGHMOND: Dr. Poland calls this a lack of respiratory etiquette. Figuring out how to stop the chain of infection is something lots of researchers want to do. Infectious disease specialist John Treanor of the University of Rochester calls it the million dollar question.

Dr. JOHN TREANOR (Infectious Disease Specialist, University of Rochester): Why is it that some people get sick and some people don't?

NEIGHMOND: Treanor says once scientists get the answer to that question, once they figure out exactly how cold viruses cause infection and how some people's immune systems keep them healthy, then science will really be able to fight the common cold.

Dr. TREANOR: One great outcome of really understanding why some people get sick is to develop medicines or vaccines that would target those mechanisms and effectively prevent respiratory illnesses or treat them.

NEIGHMOND: A great step forward, especially when you consider the average person spends about one year of their life in bed sick with a cold.

Patti Neighmond, NPR News. Transcript provided by NPR, Copyright NPR.

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