Scribble

Meg Tirrell

00:00:02

How long have you been studying colds?

Dr. Arnold Monto

00:00:05

Well, I've been studying colds now for about fifty years.

Meg Tirrell

00:00:09

This is doctor Arnold Monto.

Dr. Arnold Monto

00:00:11

I'm Professor Emeritus either public health or epidemiology, whichever one works best for you. They're all real.

Meg Tirrell

00:00:22

It's important to state that up front.

Meg Tirrell

00:00:24

And for the more than half century he's been studying colds and other respiratory illnesses, Dr. Monto has been at the University of Michigan. He's credited with discoveries as far back as during the 1968 flu pandemic, when he helped further our understanding of herd immunity with the findings that vaccinating school kids could reduce infection in entire communities. So as we get deeper into the Northern Hemisphere's cold and flu season, which typically runs from October through May with a peak in the winter months, we asked Dr. Monto, after 50 years, how much better have we become at treating the most ubiquitous illness of them all, the common cold?

Dr. Arnold Monto

00:01:00

Basically in terms of what we can do for them, it hasn't really changed.

Meg Tirrell

00:01:05

Great. I'm Meg Tirrell, CNN Medical Correspondent, filling in this week for Dr. Sanjay Gupta to ask the question: why haven't we cured the common cold? And will we ever? This is Chasing Life.

Meg Tirrell

00:01:22

'The average person has two to four colds a year, and more if you're a kid, up to 10 on average. And they're not just annoying and uncomfortable, they also cause adults to miss work and kids to miss school, which causes adults to miss work. All this adds up to an estimated $40 billion economic impact each year in the US, as of a study published in 2003, co-authored by none other than Dr. Monto.

Dr. Arnold Monto

00:01:48

We always come back to economics.

Meg Tirrell

00:01:50

Indeed. But despite that economic burden of colds, we have nothing that prevents them, like a vaccine, or that we can take to cure them once we're sick. But it's not for lack of trying.

Archival News Clip

00:02:04

The Ministry of Health research unit at Harvard Hospital Salisbury has been investigating the common code. And volunteers, human guinea pigs, have been living there in pairs for ten days at a time.

Meg Tirrell

00:02:16

In fact, for more than forty years following World War Two, there was an entire common cold research unit in Salisbury, UK.

Dr. Arnold Monto

00:02:23

They were very important. As a matter of fact, they were among the first to identify coronaviruses as a potential cause of the common cold. And the way they did it was very interesting because they had volunteers who came and allowed themselves to be inoculated.

Meg Tirrell

00:02:42

In other words, volunteers who came to live at the common cold research unit were given drops in the nose, essentially made up of snot from other people who had colds. Dr. Monto puts it a little more politely.

Dr. Arnold Monto

00:02:55

They took material from individuals who had common colds that they couldn't identify the cause and they inoculated them into other people and discovered yes we can produce a cold from it.

Meg Tirrell

00:03:13

Their work focused not just on identifying viruses that caused the common cold, but also on trying to develop antiviral drugs to treat them and vaccines to prevent them. By 1961, though, things were still slow going.

Archival News Caster

00:03:26

Until we get a vaccine for the common cold, what would you say is the best cure?

Common Cold Unit

00:03:30

Well I'm convinced that the best cure remains a couple of aspirin and a hot whiskey.

Meg Tirrell

00:03:37

Even so, over the years, a few seemingly promising drugs emerged, generating flurries of media reports that the cure for the common cold was near, but they always seemed to encounter a fatal flaw. One in the 1980s was called interferon, and administering it by spraying it up the nose seemed to help against common colds. The problem?

Dr. Arnold Monto

00:03:57

It caused nasal bleeding and other symptoms.

Meg Tirrell

00:04:01

A couple decades later, a biotech company called Viropharma advanced an antiviral drug called placoneryl, which also generated excitement. It aimed to work by stopping some of the viruses that cause common colds from being able to replicate.

Dr. Arnold Monto

00:04:15

'Looked pretty good and then we were involved in field trials in which we were using the drug in phase three studies that had gone that far. And these are the pre-licensure studies. And it was discovered that women who were on birth control had their periods affected. And the company thought that you could put a warning label on and it would get licensed, but they were dreaming because no agency would license a drug that's going to be used as extensively as one against common colds. And it it died.

Meg Tirrell

00:04:58

And that's one of the big hurdles for drugs for disease like the common cold. Though colds can cause a lot of misery, people generally get better on their own. So any medicine they take has to come with really low risks.

Dr. Arnold Monto

00:05:10

You've got to be sure that the risk benefit ratio is right. In other words, you can't use something which we would against a some more severe illness without knowing that it's very safe.

Meg Tirrell

00:05:26

The other problem is that the common cold isn't just one virus. In fact, it can be caused by more than two hundred. The most common are called rhinoviruses, which we'll hear about more in a moment, but also, as Dr. Monto mentioned before, coronaviruses.

Dr. Arnold Monto

00:05:44

They are probably the second most common virus type to cause colds. And this is one of the reasons why we were so surprised when coronaviruses showed themselves up to be a potential pandemic back when we had SARS and then a pandemic in 2020 when it arrived as a real pandemic.

Meg Tirrell

00:06:10

So typically the coronaviruses we'd seen before SARS one, about two decades ago, had been fairly mild, more similar to rhinoviruses.

Dr. Arnold Monto

00:06:20

Right, very very similar and you can't tell them apart. That's part of the problem.

Meg Tirrell

00:06:29

Attempts to develop antiviral drugs typically haven't been able to cover all the kinds of viruses that cause common colds. And it's been a similar problem for vaccines, as this newscaster found on his visit to the common cold research unit in the nineteen seventies.

Archival News Caster

00:06:43

The problem with the common cold is that many different viruses can cause it, and so far it's proved impossible to make a vaccine which will combat them all.

Meg Tirrell

00:06:52

But researchers haven't given up, and after the break, we talk with one of them.

Dr. Gary McLean

00:07:07

It's one of those things that everybody gets and everybody knows there's nothing much you can do about it, so it's kind of an interesting story, isn't it?

Meg Tirrell

00:07:17

Yeah, and scientifically I think it's so interesting too because it's not like we haven't tried.

Dr. Gary McLean

00:07:22

Exactly right. Yeah. We've tried and failed a lot.

Meg Tirrell

00:07:26

Dr. Gary McLean is one of those researchers still working to try to crack the nut that is the common cold. He's an honorary research fellow at Imperial College in London.

Dr. Gary McLean

00:07:35

I'm an immunologist, so I come from the point of view of what is it that our immune systems see when we're attacking a a virus. And the common cold is a really interesting one because we're seeing a lot of different things all the time and it's very, very difficult for the immune system to catch up. So it's one of those pathogens that's an extreme challenge. And from that point of view it attracted me as an immunologist, trying to understand how we can, you know, make the immune system better, maybe in a way.

Meg Tirrell

00:08:16

And he explains it's not just rhinoviruses and coronaviruses our immune systems have to contend with when it comes to the common cold.

Dr. Gary McLean

00:08:23

Traditionally, RSV, rhinovirus, adenovirus, coronaviruses, human metanumoviruses, there's a number of them. Altogether, all of those can cause common colds and there's a lot of them. That's why we get colds all the time.

Meg Tirrell

00:08:40

And rhinoviruses, it turns out, can be especially sneaky.

Dr. Gary McLean

00:08:44

So rhinovirus is a very small virus. It's a very geometric shape. It's a smooth kind of surface of protein that attaches to receptors on cells that are in your upper airways. Now, the first discovery of rhinoviruses was actually done at John Hopkins University in the 1950s. And it was a doctor noticed that a bunch of nurses were all suffering from a very similar upper respiratory tract infection and managed to swap them and isolate the virus, which he called what they called JH virus for John Hopkins. And then it was subsequently changed the names to rhinovirus because that comes from the Greek word rhino is nose. So it's not like influenza, which can travel deeper into the lungs or even the gut. Rhinovirus tends to stay in the nose. It's very fast, it's a weapon of speed. And as we know, there are a lot of them, and they're very dangerous little customers because we're always trying to catch up with our immunity to these viruses.

Meg Tirrell

00:09:58

And we heard from Dr. Monto about some of the approaches to trying to develop antiviral drugs to treat common colds over the years. But there was a lot of work to try to make vaccines to prevent them as well.

Dr. Gary McLean

00:10:10

The old traditional approach with a a new pathogen or a virus such as this was you'd grow as much of it as you could in the lamb, and then you take some chemicals to inactivate it so that it becomes non infectious. That end product is still what we call immunogenic, which means if you if you put it into a animal or a human, it would be recognized and an immune response would be made against it. And of course, these approaches tended to fail because they didn't fully anticipate the breadth of different strains of rhinobirus. So this was in the probably the nineteen seventies when those kind of approaches were stopped because it was established that it was just too difficult, technically impossible for us to generate immunity to all of those different rhinovirus strains. And at the same time it was considered, well, it's not really a very dangerous virus. It doesn't kill many people. There are other things that are perhaps a little more important to focus vaccine approaches on.

Meg Tirrell

00:11:24

And the rhinovirus' humble attributes may be part of what make it such a successful virus.

Dr. Gary McLean

00:11:29

I often tell students that I think it's the most perfectly adapted human pathogen because it's so fast, it transmits easy, it doesn't cause very severe disease, which is what the virus wants, right? Remember it's a parasite. It needs us to make copies of itself. That's its sole aim, go to the next person, the next nose. And it does that very, very well.

Meg Tirrell

00:11:55

That's the thing about viruses, like it it's it's sort of perfect if it can infect you and you can carry it around and it makes you symptomatic enough that you sneeze on other people, but not so symptomatic that you stay home and don't sneeze on other people.

Dr. Gary McLean

00:12:09

Put you in bed. Not at all. It wants you to be out, yeah, spreading. Yeah, yep. Exactly, and it does that brilliantly. So will we be able to stop it? I don't know. I hope so. It's not gonna stop me from trying.

Meg Tirrell

00:12:27

'So, how's he doing it? Well, one of the biggest challenges is figuring out how to train the immune system to recognize all or a lot of the different strains of rhinovirus out there. Often, vaccines show the immune system the outside pieces of a virus. Think of those infamous spike proteins sticking out of the COVID-19 virus, for example. So that the next time we encounter a virus in the wild, the immune system will say, hey, that's not supposed to be here and be ready to mount its attack. But it turns out there's a target on the inside of rhinoviruses that seems to be more conserved across different strains. So that's what Dr. McLean's vaccine focuses on. It aims to stimulate part of our immune system that uses T cells, which can seek out and destroy virally infected cells. The goal, at least to start, is to protect people for whom a common cold might be especially dangerous, those with chronic lung disease.

Dr. Gary McLean

00:13:20

They have the most severe inflammation that can become life threatening. It's triggered by rhinoviruses and there's no specific cure for that. If we were able to, you know, reset immunity in those people and at the same time protect against new rhinovirus infections, that would go a long way towards stopping hospitalizations. If that works in COPD, then that can be translated into other chronic lung diseases such as asthma, and then also the elderly and and those whose whose immune systems are not as powerful and strong. And then eventually one day it could be applicable to humans that are generally considered healthy, but it might take a while.

Meg Tirrell

00:14:10

How long? Well, for about the last decade, McLean says he's been working to expand how many different types of rhinoviruses can be covered by his vaccine in animals. It's not yet in human clinical trials, which themselves take years before a vaccine might be licensed for broad use. But he says he's been making progress.

Dr. Gary McLean

00:14:29

I'm pleased to say that it's kept incrementally working each each time. Getting better and better and better, but of course still far away from covering all of those a hundred and eighty types of rhinovirus.

Meg Tirrell

00:14:42

I'm beginning to think you have to have a certain level of optimism to be able to work on the common cold. And we should note one thing we heard from all the experts we talked with is that because rhinoviruses target the nose, a nasal spray would likely be the best approach to stopping it. It's been tried with COVID, and there is an approved nasal spray flu vaccine, but it's not anywhere close yet for rhinoviruses. So until then, we're stuck trying to treat our symptoms. So what do the experts do?

Dr. Gary McLean

00:15:13

I drink lots of water. I will also take vitamin C. Apart from that, yeah, nothing really. I I just try and let it run its course and try not to get dehydrated.

Dr. Arnold Monto

00:15:25

Typically I'll take some antihistamines early because some of the original antihistamines, the ones that make you sleepy have have a minor effect. And then do what most people do and that is suffer. Try to stay away from other people.

Meg Tirrell

00:15:48

And if all else fails, there's always

Common Cold Unit

00:15:51

A couple of aspirins and a hot whiskey.

Meg Tirrell

00:15:54

Okay, maybe not, but I am wishing everyone the best of luck this cold and flu season. Sanjay will be back on Tuesday with the next installment of Paging Dr. Gupta. Thanks for listening.