Herd Immunity

[Tabitha8]

A simple title for what I think is probably a complex subject.

If we have herd immunity to an illness as a result of vaccinating our children, how is that maintained given that we don't vaccinate ourselves, the grandparents, our neighbours, etc?

And you most certainly can have a little herd immunity depending on how you define it.

I'm afraid that you are not the keeper of definitions of herd immunity bumbley. You can define it as the threshold, I prefer to use other definitions which I think are clearer.

I'm not avoiding anything Elaine, you just keep talking about reducing susceptibles/transmission as if any reduction can be classified as herd immunity despite the fact that pretty much every definition of herd immunity/community immunity has said that a significant proportion are required to have that effect. Do you think having 3 immune people in a group of 1,000 would be classed as herd/community immunity?

Bumblymummy, do you think children should be vaccinated against polio or not? Yes or no?

Ok then, define it Elaine. (as I asked way back at the start) What are you talking about when you are using the term 'herd immunity'. Are you referring to the proportion of the population who are immune or are you talking about the protective effect that can be conferred when a significant proportion of the population are immune?

seeker, it has nothing to do with me whether other people vaccinate their children against polio or not. I don't mind whether they do or not. What does that have to do with this thread?

It has do with the thread in two distinct ways.

1)Do you think your children would be safe from polio in an unvaccinated community?
And

2. It is customary in a debate to declare an interest. If you are an anti vaccination campaigner then it would be courteous to be open about it.

Do I think they'd be 'safe' from contracting it in an unvaccinated community? No, why would they be? They'd have the same chance of catching it as anyone else.

at anti-vaccine campaigner. No, I'm not.

Ah. And polio isn't something to fear, then?

...with the exception that anytime she can, bm is on these threads dismissing vaccines. Unrelentingly. The only positive thing I've ever seen her mention is that inhalable vaccines look 'interesting'. I have a strong suspicion that with the advent and rolling out of these new-style vaccines, bm'll find good reason to diss these too.

Wow, you have a short term memory BFG. We spent quite a lot of time discussing vaccinating older children/adults against things like rubella and CP not too long ago.

And don't forget the mysterious aluminium issue.

seeker, I guess you could fear it if you wanted too.

To*

Bm- I am really wondering why you won't answer straight questions with straight answers.

Yes I would fear polio. Because I am old enough to remember when there were epidemics of it.

Would you?

If you're not avoiding my question bm, then pls answer. you clearly are avoiding it!

Do you think it matters for disease transmission if R is 3 or 1.1?

I think you should get on with anwering those two questions first bm.

With my short term memory I retained two things:

wrt rubella: you proposed no one (not even siblings) should be vaccinated to protect someone else. You do think it OK however for women of childbearing age should check immunity regularly until menopause and before she decides to become pregnant, vaccinate then.

wrt CP: again, vaccinating only women if they want children, after testing for immunity.

My longer term memory (this is fuzzier) says you are OK with vaccinating against a terrible disease (not sure which one, it might have even been hypothetical) only if you come directly into contact with an ill person.

I suppose I disregard these things as I feel they are so unworkable as to not really count as being Ok about some vaccinations. It's a bit like me saying I've nothing against football on Saturday's in months with 29 days...oh, and only between 12-2pm.

No, I wouldn't.

I bet there are things that I fear that you don't though. Everyone is different.

EB, you're still avoiding mine. Yes, I think it matters. Can you answer my questions now?

Do you think having 3 immune people in a group of 1,000 would be classed as herd/community immunity?

What are you talking about when you are using the term 'herd immunity'. Are you referring to the proportion of the population who are immune or are you talking about the protective effect that can be conferred when a significant proportion of the population are immune?

I'm not sure how someone can be considered 'anti vaccine' if they suggest it even for certain groups. I'm pretty sure people who are genuinely anti-vaccine wouldn't agree with that but hey-ho.

Yes, your short term memory is poor.

You're not anti-vax - I'm not anti-football either.

People are vaccinated in childhood, so they still have immunity in adulthood most of the time. Children are more vulnerable to childhood illnesses. Their immune system is less developed, they are more vulnerable to the effects of the disease, and they mix with close contact at school. That is why vaccination programmes ate aimed at children.

So, bm. Imagine a hypothetical situation where you live in an area where polio is endemic and nobody's vaccinated. There are cases in your child's school. Are you saying that you would be perfectly happy with your children going to school? Because this what parents in some parts of Africa have to do. And you were completely dismissive of their efforts to get the vaccine for their children and said they should concentrate their efforts on getting water.

Actually tempernillo, most childhood diseases are more risky in adulthood. Pushing the disease into adulthood is actually recognised as a perverse effect of vaccination.

Seeker, I didn't say that they should 'concentrate their efforts on getting water' I do still think that you should move away from this comparison with Africa though. Polio may be quite far down their list as far as worries about their children go. As I've said before, it's not really a fair comparison.

Vaccination is actually quite high up the list of priorities of people in the developing countries. It is a way of protecting the children they have now.

The comparison is entirely valid. If you expect a mother in the developing world to send her unvaccinated child to school during a polio outbreak, the least you can do is say whether you would do the same.

Answer the question.

Different diseases have different thresholds. Measles requires over 90% immunity threshold for an outbreak to be contained. Smallpox requires somewhere around 80%.

'Pushing the disease into adulthood is actually recognised as a perverse effect of vaccination.'

...but remember that with herd immunity, that effect is avoidable if enough people in a population are vaccinated (and boosters are available).