Modelling measles re-emergence as a result of waning of immunity in vaccinated populations

[ema-adama]

However, re-emergence is possible to occur several decades after introduction of high levels of vaccination.

Although waning of humoral immunity in vaccinees is widely observed, re-emergence of measles in highly vaccinated populations depends on parameters for which better estimates are needed.

http://www.sciencedirect.com/science...225356116f4469

Very interesting.

Underlining mine

[ursusarctos]

Originally Posted by ema-adama

http://www.sciencedirect.com/science...225356116f4469

Very interesting.

Underlining mine

Interesting indeed. And I thought vaccines were supposed to prevent the disease altogether

[shuttlt]

Originally Posted by ursusarctos

Interesting indeed. And I thought vaccines were supposed to prevent the disease altogether

Depends on the vaccine, depends on the herd immunity threshold. At worst it means that you may need a booster at some point. The real question for me is how hard such a booster would be to administer on a mass scale.

Anybody who says that vaccines prevent the disease altogether are over-simplifying.

[ursusarctos]

Originally Posted by shuttlt

Anybody who says that vaccines prevent the disease altogether are over-simplifying.

Yep. That's kind of what I was getting at

[Th1Th2]

How can vaccines prevent disease when the principle of vaccination is the inoculation of the disease? The medical community always claim that vaccines protect us. Protect from where? Those diseases that had already been injected in the bloodstream? That's why it's better to stay vaccine-free to be disease-free.

[shuttlt]

Originally Posted by Th1Th2

How can vaccines prevent disease when the principle of vaccination is the inoculation of the disease?

I don't understand what you mean. They don't simply give you a full on case of measles when they give you a measles vaccine. I'm sure I'm missunderstood you, but I'm not sure how I should be reading this.

Originally Posted by Th1Th2

The medical community always claim that vaccines protect us.

I agree

Originally Posted by Th1Th2

Protect from where?

Do you mean 'what' rather than 'where'?

Originally Posted by Th1Th2

Those diseases that had already been injected in the bloodstream?

Yes, but they don't vaccinate people by giving them measles, not in a simplistic sense anyhow.

Originally Posted by Th1Th2

That's why it's better to stay vaccine-free to be disease-free.

But if we didn't have vaccines we would all get the disease, so you almost certainly wouldn't be disease free.

[Th1Th2]

Originally Posted by shuttlt

Yes, but they don't vaccinate people by giving them measles, not in a simplistic sense anyhow.

How can there be an immune response without the disease? Adjuvants? You tell me.

[shuttlt]

Originally Posted by Th1Th2

How can there be an immune response without the disease? Adjuvants? You tell me.

Sure, but an immune response isn't the same as coming down with the disease. If you feel that it is, then fine, but that just means that we have to be a lot more granular about what we mean when we talk about having the disease. It certainly isn't having the disease in the sense of having an immune response that vaccines are supposed to prevent. What vacines are trying to prevent is people getting sick in the sense of infectious, or sick in the sense of being at risk of complications.

[ema-adama]

Originally Posted by shuttlt

What vacines are trying to prevent is people getting sick in the sense of infectious, or sick in the sense of being at risk of complications.

This is a bit naughty, but do you know what shedding is? And which vaccines shed?

[shuttlt]

Originally Posted by ema-adama

This is a bit naughty, but do you know what shedding is?

Yes, you've caught me being other than precise. Clearly if vaccine shedding causes enough new cases that the cost/benifit turns against the vaccine, then shedding is a problem. I kind of felt saying that the vaccine was 'trying to prevent people getting sick in the sense of infectious' covered the fact that an on balance reduction in the number of infectious people is an aim of vaccination. To clarify, that is what I meant.

Originally Posted by ema-adama

And which vaccines shed?

I'm sure you'd be able to provide a better list than me. I'm still pretty vague on the majority of vaccines.

[Th1Th2]

Originally Posted by shuttlt

Sure, but an immune response isn't the same as coming down with the disease. It certainly isn't having the disease in the sense of having an immune response that vaccines are supposed to prevent.

Does it mean vaccinated people who developed an immune response are getting something else from disease-specific vaccines?

Originally Posted by shuttlt

What vacines are trying to prevent is people getting sick in the sense of infectious, or sick in the sense of being at risk of complications.

Vaccines are not designed to prevent diseases rather they facilitate the development of diseases.

[shuttlt]

Originally Posted by Th1Th2

Does it mean vaccinated people who developed an immune response are getting something else from disease-specific vaccines?

I don't understand what you're saying.

Originally Posted by Th1Th2

Vaccines are not designed to prevent diseases rather they facilitate the development of diseases.

OK. Going with what I think your terminology is.... vaccines are designed to facilitate a version of the illness that is sufficiently milder than a case of illness caught naturally that the cost/benifit of vaccination makes the exercise worth while [gasps for breath!]

[Th1Th2]

Originally Posted by shuttlt

I don't understand what you're saying.

What I meant is that the disease-causing microorganisms inside the vaccine can induce an immune response. Agree?

Originally Posted by shuttlt

OK. Going with what I think your terminology is.... vaccines are designed to facilitate a version of the illness that is sufficiently milder than a case of illness caught naturally that the cost/benifit of vaccination makes the exercise worth while [gasps for breath!]

When you say illness you mean the disease but a mild one and not the real one since it's just a version, right?

[shuttlt]

Originally Posted by Th1Th2

What I meant is that the disease-causing microorganisms inside the vaccine can induce an immune response. Agree?

OK. I agree, I think.

Originally Posted by Th1Th2

When you say illness you mean the disease but a mild one and not the real one since it's just a version, right?

I was trying to use what I thought to be your terminology to describe my view, and now you're paraphrasing it back to me... so we may still be missing each other, but this looks right.

[Th1Th2]

Originally Posted by shuttlt

I was trying to use what I thought to be your terminology to describe my view, and now you're paraphrasing it back to me... so we may still be missing each other, but this looks right.

This is simple. In order to develop immunity, one has to be exposed to the disease and that is precisely what vaccines do---it injects the disease. Unless there is something else in the vaccine that triggers the immune system or enhances the immune response. Hmmm...

[shuttlt]

Originally Posted by Th1Th2

This is simple. In order to develop immunity, one has to be exposed to the disease and that is precisely what vaccines do---it injects the disease. Unless there is something else in the vaccine that triggers the immune system or enhances the immune response. Hmmm...

There are quibbles like dead/live pathogen etc... but I agree with your post sufficiently that I think we can move on.

[ema-adama]

Originally Posted by shuttlt

Depends on the vaccine, depends on the herd immunity threshold. At worst it means that you may need a booster at some point. The real question for me is how hard such a booster would be to administer on a mass scale.

I did not manage to understand just how the measles would re-emerge in a highly vaccinated population.

Why do you think boosters are the answer?

[shuttlt]

Originally Posted by ema-adama

I did not manage to understand just how the measles would re-emerge in a highly vaccinated population.

Depends on the vaccine, depends on the herd immunity threshold. At worst it means that you may need a booster at some point. The real question for me is how hard such a booster would be to administer on a mass scale.

Why do you think boosters are the answer?

It probably wouldn't. I was trying to make my statement as general as possible. If immunity tales off at some point (30 years, 40 years...) and you lose the older segment of the population to age who have been exposed to the vaccine in the wild, you could end up struggling to stay the right side of the herd immunity threshold.

[ema-adama]

Originally Posted by shuttlt

It probably wouldn't. I was trying to make my statement as general as possible. If immunity tales off at some point (30 years, 40 years...) and you lose the older segment of the population to age who have been exposed to the vaccine in the wild, you could end up struggling to stay the right side of the herd immunity threshold.

If you have any thoughts on the following I would be interested

What mechanism would allow measles to re-emerge?
How many generations would recquire vaccination, to eliminate the virus?

I wish I could know what age group they are talking about. As they mention that vaccine modified measles and classical measles would re-emerge in the same age group.
To be honest, I have no idea what vaccine modified measles even means. (

[shuttlt]

Originally Posted by ema-adama

If you have any thoughts on the following I would be interested

What mechanism would allow measles to re-emerge?

The only mechanism I can think of would be herd immunity falling below threshold.

Originally Posted by ema-adama

How many generations would recquire vaccination, to eliminate the virus?

I guess that depends what you mean by eliminate. If you are continually having new cases flying in from places where you aren't vaccinating, then never. Taking into account different vaccination policy in different countries would make this a non trivial calculation to do in anything other than a made up context. Could still be worth doing though.

Originally Posted by ema-adama

I wish I could know what age group they are talking about. As they mention that vaccine modified measles and classical measles would re-emerge in the same age group.
To be honest, I have no idea what vaccine modified measles even means. (

I'm not sure either. Could it be measles caused by vaccines containing measles that has been artificially modified/weakened?