Science Questions

Why can we not gain immunity to the common cold?

Sun, 6th Sep 2009

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Foram Joshi asked:

Why can we not gain immunity to the common cold?


Chris -   I wish I knew the answer to that.  Itís actually just simple numbers.  There are two reasons for this.  One is to be immune to something, your immune system has to see it in the first place.  So you have to be infected with the thing, so you then learn to neutralize it in the future.  Now, that would be simple if there was one virus, but in fact there are hundreds.

If you look at the rhinovirus family, which is the cause of the common cold, around most of the year, there is about a hundred of those.  If you look at the enterovirus family, thereís about a hundred of those.  There is 50 or 40 adenoviruses, many of which cause upper respiratory and eye infections.  Then there are the corona viruses, the parainfluenza viruses, the influenza viruses and to add insult to injury, these viruses also mutate.  So not only are there hundreds of them around for you to get your immune systemís head around but also they are moving target.  They are changing their molecular appearance, so even if you have learned to recognize it, thereís no guarantee that youíll recognize it again the next time.  And given that there are all these hundreds of viruses and the average person gets about two or three colds per year, thatís three life times worth of cold infections before youíve actually got any chance of being immune to all of them, by which time they probably have changed.

So, I donít think thereís really any prospect of ever being able to cure the common cold with the exception that what scientist including Steven Legit who is a researcher of University of Maryland had done, is theyíve sequenced genetically all of the rhinoviruses so far.  And they know how they divide up to a little subfamilies and it might be that if you a made a vaccine based around some members of some of those subfamilies, then every time you immunize someone who gets one of the subfamilies you are protected against all the other members of that family.  So you could make a vaccine but it would have probably be based around lots and lots a different members and probably be unfeasible.  Who knows, letís hope though that we come up with some kind of common cold cure soon because since you have children youíre into a whole different ball game.


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foram joshi asked the Naked Scientists: Dear Naked Scientists, † my question is: why do we catch colds so often? Why do we not become immune to diseases like the common cold? What do you think? foram joshi , Tue, 18th Aug 2009

We do gain immunity to the common cold, we never get the same cold twice!! However there are so many different strains of the common cold, each time we come into contact with a new strain, we have to go through the process of having the cold in order to gain the immunity! Variola, Tue, 18th Aug 2009

Variola, the TNS 'Pox in Residence' has given the definitive answer.

Google 'Common Cold Unit', I'm sure you will find plenty of info on this government sponsored research unit, which was abandoned with total failure. Don_1, Tue, 18th Aug 2009

I have never had the common cold OR the flu in my entire life.
I start to believe I have a natural immunity against rhinoviruses and Infuenza.

I do have a strange case of asthma like auto-immune bronchial disorder. Strange in the sense of: it triggers when I don't get enough sleep for two-three days in a row, but I don't have any specific allergies and I'm not having episodes caused by the usual asthma inducing factors.

Maybe these conditions are related, maybe not. But I'm pretty sure I'm not the only guy on the world with natural rhinovirus/Influenza immunity. Nizzle, Tue, 18th Aug 2009

Behold, the only man in the world not to have had 'man flu'! See I knew there had to be one!!! 

Every other man, they get a slight sniffle and they are convinced they need round the clock nursing!! Variola, Tue, 18th Aug 2009

If the deffinition of 'flu is " a cold, but so bad you can't get out of bed" then I have never had 'flu. Perhaps serological analysis would tell me something else.
On the other hand, I generally get a cold or two each Winter- they just don't bother me much. I guess I just have a robust immune system.
Is "Man 'flu" the opposite of Bird 'flu"? Bored chemist, Tue, 18th Aug 2009

Nope bird 'flu is actually real, and doesn't come as the result of a minor sniffle.  Variola, Tue, 18th Aug 2009

That is actually a very interesting question you've got there foram joshi. Such a common illness and no vaccine?

Well as already mentioned there are about a ton of different types of cold (To us, they all seem the same). The viruses causing colds are called rhinoviruses, and there are around 100 of them (Depends who you ask, i've seen the number vary between 98 and 103 rhinoviruses).

Here is the deal, and actually the web is full of the news at the moment. Scientists have just managed to discover the genetic make-up of all the known Rhinoviruses! What they discovered was rather astonishing. They discovered that some of the genetic make-up is supposedly identical between all rhinoviruses, which actually will enable us to start thinking of how to produce the vaccines against cold. DrChemistry, Tue, 18th Aug 2009

HIPV's,enteroviruses,coronaviruses and adenoviruses also cause common colds too. 

Yep,I remember reading a journal article on it a short while back, I will see if i can find it again.

Variola, Tue, 18th Aug 2009

Nope bird 'flu is actually real, and doesn't come as the result of a minor sniffle. 

I think I caught this, I opened the window and in flew enza. Don_1, Wed, 19th Aug 2009

HIPV's,enteroviruses,coronaviruses and adenoviruses also cause common colds too. 

Yep,I remember reading a journal article on it a short while back, I will see if i can find it again.

I take that back. Variola is right. Enteroviruses and Rhinoviruses are however from the same Family. The problem with using general terms are that we forget to mention sub-divisions. So some of the other viruses that were mentioned can cause cold symptoms, but also other symptoms not related with colds. It all depends on small differences. Putting that aside, the main message was that a vaccine against rhinoviruses (Unable to find anything about the discovery of the genetic make-up of the other viruses), is on its way.  DrChemistry, Wed, 19th Aug 2009

And let's not forget that virus genomes mutate, so a vaccin has to be reinvented everytime a virus reinvents itself (as long as the mutation occurs in membrane component coding genes) Nizzle, Wed, 19th Aug 2009

When the vaccine is rendered useless depends entirely on how it was constructed and what genes that mutate. If 75% of the genetic make-up is the same for all rhinoviruses, I wouldnt worry about inefficient vaccines just yet. If it does go and get nasty, I see no problem in reinventing the vaccine. Those who wish to stay away from colds probably wont mind either. DrChemistry, Wed, 19th Aug 2009

Sorry I was just being pedantic.  As regards to vaccines, a vaccine against rhinovirus would not work against an enterovirus despite them being from the same genus. ( I think!)
As Nizzle pointed out, if the genetic similarity involves the ENV part of the genome then we could be in luck. However given the large size of rhinovirus family shows the variation, I think it will be difficult to construct a vaccine that will be affective against 75% of them. And then there are all the inherent problems that trying a new vaccines has surrounding it.
Mind you, it does give some scope for using rhinovirus in gene therapy. Variola, Wed, 19th Aug 2009

I dont think a Rhinovirus vaccine would work against enteroviruses either I do not think that is likely at all, but well, I could be wrong. Once again its all in the details

Do you mean it will be difficult to contruct a vaccine affective against 75% of all rhinoviruses, or it will be difficult to construct a vaccine that will make affective use of the 75% similarity in all the rhinoviruses? Sorry, didn't quite get that no matter how many times I read it. Might be my poor level of english gramma DrChemistry, Wed, 19th Aug 2009

Well I typed it with confidence, but then had a moment of not being so sure! Without looking at the genome both I wasn't so confident! But I am reasonably sure it wouldn't work.

No it is my poor quality of typing! I was thinking over the problem while typing, and it came out confused!

I meant that given that 75% of the genome is the same, but also given that the rhinovirus family is so large,it would be difficult to develop a vaccine against all of them.
We show no immunity from other rhinoviruses no matter how many we have.i.e if we have 10 different rhinovirus infections, we can still get the other 90 or so that are left. (in theory). That shows just how diverse the rhinovirus family is. It's not as straightforward as developing one against a 4 or 5 strain genus, although that's not simple in itself.
I am also not sure there will be much finding put into finding a vaccine because colds, although a nuisance are rarely life threatening.
Variola, Wed, 19th Aug 2009

I'm not that well informed in the area of genetics, but to me it sounds a bit like a fairytale if we could kill enteroviruses with a rhinovirus vaccine. I have seen no such predictions wirtten anywhere, at all.

I just wanted to make sure I understood it correctly. Would be horrific If I replied on an idea I had misunderstood

I myself would probably not take a vaccine against colds. There are better ways to get rid of it than taking a bunch of chemicals, so for me it does not matter if the vaccine is against 1 type of rhinovirus, or all 100 of them.

P.s. Allegdly scientists believed they could make one vaccine against the majority of them because of the way the Rhinoviruses were built up.  I have to admit though that I read it as a very not-well developed extract, so I am more than willing to take your point of view. DrChemistry, Thu, 20th Aug 2009

Is it an evolutionary thing?
We don't die of colds and they don't seriously affect our reproducing capability so we only need to 'tolerate' them. As in lots of parasite - host relationships there is a certain amount of tolerance and a certain amount of co operation between the two. The rhinovirus may have been protecting us from other things in our system and we never knew it.
The fact that people have spent decades rushing to the Doctor at the first sign of a cold (and expecting to be given something for it) has probably meant that antibiotics have been used far more than they should have been.
An early night and a lemsip / whisky / whatever you fancy is usually the best way to deal with and to get resistant to things like a cold. lyner, Mon, 24th Aug 2009

Chris should be answering this really, as he is the forum expert of immunology.

It is evolution in one sense, our beautifully clever immune system has developed and adapted alongside viruses such as rhinovirus, hence why it is so well honed to prevent us suffering the ill-effects of pathogens. It is more than just WBCs mooching about in the blood system waiting to pounce, it is a whole complex system of communication. There has indeed been some speculation that the alleged 'junk' DNA  found in our genome shares similarities with the genome of retroviruses, leading to the conclusion that somewhere along the evolutionary path,these 'alien' genes have transcribed into our development. 
However I don't consider it as an endosymbiotic relationship though, as if it was we would not have developed the targeted immune response to the rhinoviruses.

Yes unfortunately medicine was so impressed with itself for creating antimicrobials, that we pressed ahead hailing them as wonder drugs. Science, in it's proud naivety didn't realise that something so tiny, it can only been seen with a microscope would manage to outwit and outdo them at every turn.

Basically,relieving the symptoms and taking it easy on yourself is the only thing you can do, while your clever immune system dispatches the virus, while of course taking its name and number for future reference! Good nutrition is helpful too, nothing like a bunch of co-factors and prosthetic groups to keep the body happy!
Variola, Wed, 26th Aug 2009

Thanks for the clear and comprehensive answers you all came up with for this question; I think I also gave a fairly thorough answer on the podcast, which you can access via the link above.

Chris chris, Tue, 8th Sep 2009

never had a cold ever.i was told it is because i had diptheria as a baby.i am well into my seventys yorkie39, Sat, 11th Apr 2015

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