The connection between cold weather and catching a cold

Read the Full Transcript

• John Yang:

  A cold nose, the old saying goes may be good for dogs. But for you and me, maybe not so much. New research suggests that cold weather may actually affect the body's immune response, making us more susceptible to COVID, colds, flu and other upper respiratory infections.

  Dr. Benjamin Bleier is a sinus specialist at Mass Eye and Ear in Boston. He teaches at the Harvard Medical School and he's the senior author of this study.

  Dr. Buyer, I want to — have I got this right, that when it comes to fighting viruses, there is more going on, maybe not right under our noses, but more going on in our noses than previously understood?

  Dr. Benjamin Bleier, Mass Eye and Ear: Yes, that's right. In fact, what our study found, which takes off on some work we had done previously, several years ago, was that inside the front of our noses, when we're exposed to a virus, there's a whole sort of war going on. Whereas when our nose detects the presence of a virus, the cells released these swarms of bubbles, which we call vesicles, that have several functions. One is they actually bind to the virus. They stick to the viruses themselves sort of mopping up the virus before it has a chance to infect ourselves. But not only that, but these bubbles actually directly kill the virus when they bind to it. So essentially, these viruses don't have a chance to infect ourselves because of these bubbles, these vesicles that get into our mucous.

• John Yang:

  And how does the cold affect us? Or how does this change when it gets cold?

• Dr. Benjamin Bleier:

  Well, what we found was that when the front of the nose is exposed to cold, and the way we looked at this is we actually took healthy volunteers, and we measure the temperature of the front of their nose at room temperature. And then at about 40 degrees Fahrenheit. What we found is that the front of the nose, the temperature drops by about five degrees Celsius, or nine degrees Fahrenheit. And in effect, just that modest drop in temperature decreases all of these immune functions of these little vesicles by about half. And so, what that translates to is that there's about twice as much virus able to get into our cells and replicate just after exposure to this small drop in air temperature.

• John Yang:

  Is there a threshold, is there a temperature which below this really gets to be a problem?

• Dr. Benjamin Bleier:

  Well, we only measured really this one drop. And we picked this number, because this is sort of a typical winter that at least we would see here up in Boston. And what we found was that we could actually quantify and relate the degree of temperature drop to specific changes, or decreases in our ability to fight these viruses. So, this is really the first time that we've discovered a quantitative mechanism for how the cold impacts our nasal immunity and our ability to fight off viruses.

• John Yang:

  And does this change the thinking about why winter is sort of cold and flu season?

• Dr. Benjamin Bleier:

  Well, this does, because you know, prior to this study, there's been a lot of sort of speculation as to why we see this very constant pattern year over year as the temperature drops, we see higher rates of respiratory infections. People used to say that, well, maybe people are gathering more indoors and that's why. But we all know that in our modern society, we're indoors all year round. And other studies have looked at this, where people get together, for example, during sports events, and they don't see these same types of effects.

  So, really, we wanted to look at an actual mechanism that we could quantify. And this changes the way that we look at this because now we know that the nose really has a very important role in not only protecting us from respiratory viruses, but also how that protection is impaired when we're exposed to again, very, very modest changes in temperature.

• John Yang:

  Are there implications for how doctors treat colds and flu or prevent colds and flu?

• Dr. Benjamin Bleier:

  Yeah, so the type of effect we're talking about is part of what we call our innate immune system. This is the part of our immune system that immediately protects us against viruses within minutes to hours of being exposed. What this tells us is, first of all, that things like masking are still very important because not only does this prevent us from inhaling the virus for those viral particles to get into our nose, but we also think that in the cold months, maybe these masks also maintain it this cushion of warm air in front of our noses, and maybe prevent this reduction in temperature. But this also tells us that maybe as potential preventative therapies in the future, we could leverage some of our discoveries to actually fool the nose into thinking that a virus is present, and increase or upregulate, this dramatic immune response and maybe prevent us from getting infected in the first place.

• John Yang:

  Regardless of the temperature?

• Dr. Benjamin Bleier:

  Exactly.

• John Yang:

  Dr. Benjamin Bleier of Mass Eye and Ear in Harvard Medical School, thank you very much.

• Dr. Benjamin Bleier:

  Thank you.

Improved audio player available on our mobile page