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Life Sciences => Cells, Microbes & Viruses => Topic started by: scientizscht on 08/07/2018 01:13:35

Title: Why you dont get reinfected on the same season by cold virii?
Post by: scientizscht on 08/07/2018 01:13:35
Hello!

I try to understand how common cold viruses or rhinoviruses work.

So you have 160 different serotypes. However, you only get one cold per season. Why that?
Shouldn't you get another infection from a different serotype?
Title: Re: Why you dont get reinfected on the same season by cold virii?
Post by: evan_au on 08/07/2018 03:58:47
Quote from: scientizscht
you only get one cold per season
Maybe if you are hermit, and don't get out much...

The following website suggests that adults get 2-4 colds per year, and children 6-10 per year.
...and schoolteachers seem to pick up anything that is going around!
See: https://www.webmd.com/cold-and-flu/common_cold_overview

As you say, there are many types of virus causing the "common cold", and many strains of each virus.
While infection by one strain may provide some partial immunity from closely-related strains of the same virus, it provides no protection against other viruses.
See: https://en.wikipedia.org/wiki/Common_cold#Viruses
Title: Re: Why you dont get reinfected on the same season by cold virii?
Post by: scientizscht on 08/07/2018 16:21:59
Why some People never get a cold for years?

Also, if each cold you get, you get permanent immunity to that strain, why haven't you managed to be immunised for all strains by your 30s when you would have get 120 colds in total?
Title: Re: Why you dont get reinfected on the same season by cold virii?
Post by: evan_au on 08/07/2018 23:14:04
Quote from: scientizscht
why haven't you managed to be immunised for all strains by your 30s when you would have get 120 colds in total?
Immunity does improve with time - that is one reason that adults get fewer colds than children (another reason is that adults are more disciplined about washing hands and sneezing into a tissue).

But the rate of cold infection does not drop to zero as you get older - this is because viruses continually mutate (another reason is that our immune systems get weaker as we age). Viruses don't have the complex error checking and correction mechanisms that more complex organisms require, so mutations are fairly common.

Mutations that are different enough to hide from the immune system will then spread through the population, causing another wave of cold infections.
See: https://en.wikipedia.org/wiki/Virus#Genetic_mutation

Quote
Why some People never get a cold for years?
I thin if you checked their immune system for sensitivity to various viruses, you would find that they had been exposed, but they showed few symptoms of the infection.

Ironically, most of the classic cold symptoms (runny nose, fever, headache) are not caused by the virus itself, but by your body's immune response to the virus.

If you have a weak immune system, you may not get symptoms of a virus infection - but a cold could kill you.
Title: Re: Why you dont get reinfected on the same season by cold virii?
Post by: scientizscht on 09/07/2018 06:59:14
Quote from: scientizscht
why haven't you managed to be immunised for all strains by your 30s when you would have get 120 colds in total?
Immunity does improve with time - that is one reason that adults get fewer colds than children (another reason is that adults are more disciplined about washing hands and sneezing into a tissue).

But the rate of cold infection does not drop to zero as you get older - this is because viruses continually mutate (another reason is that our immune systems get weaker as we age). Viruses don't have the complex error checking and correction mechanisms that more complex organisms require, so mutations are fairly common.

Mutations that are different enough to hide from the immune system will then spread through the population, causing another wave of cold infections.
See: https://en.wikipedia.org/wiki/Virus#Genetic_mutation

Quote
Why some People never get a cold for years?
I thin if you checked their immune system for sensitivity to various viruses, you would find that they had been exposed, but they showed few symptoms of the infection.

Ironically, most of the classic cold symptoms (runny nose, fever, headache) are not caused by the virus itself, but by your body's immune response to the virus.

If you have a weak immune system, you may not get symptoms of a virus infection - but a cold could kill you.

You contradict yourself.

If weak immune system leads to fewer symptomatic colds, why babies and elderly get more of them?