herd immunity

[ema-adama]

Empirical observations confirm epidemic theory, showing that the probability of a diphtheria epidemic is reduced to near the vanishing point when 50 to 60 percent of the population have been rendered resistant either by previous infection or immunization. When a population has a level of lifelong immunity to a certain disease such that an epidemic of that disease cannot occur, the population is said to have herd immunity.

http://www.answers.com/topic/herd-immunity

Bolding and emphasis mine

This is rather interesting for me. If it is one of the cornerstones to herd immunity that there is lifelong immunity, how can vaccinations be attributed for the lack of infectious disease? Or is it not common knowledge that vaccination does not confer lifelong immunity?

I also found it interesting that when looking at agent, environment and host, they are looking only at infection with the disease, not how the host responds to the disease. This is where I would think it would be important to assess the overall health of the host to establish the outcome of the disease....

I am still trying to get my head around all of this. Just the fact alone that lifelong immunity is required makes me at the whole herd immunity concept as this argument is only made with such vigor for babies - that adults are causing a huge drop in herd immunity (and themselves more at risk if they become ill with a childhood disease) seems to escape doctors attention.... ie parents are abusing herd immunity by not vaccinating their child. :

I am sure this has been covered extensively here on MDC... I would be interested to read more about it

[Gnatty]

Originally Posted by ema-adama

Or is it not common knowledge that vaccination does not confer lifelong immunity?

I don't think it is. I know I was not aware of that prior to researching. Now that I know that if my child gets something they're immune for life (instead of being vaccinated and having to be revaccinated when it wears off) I am much more comfortable going without.

I'm also thankful I know a lot of non-vax families-- because otherwise he might not be exposed to some of those things that he should be.

[Gitti]

Originally Posted by Gnatty

I'm also thankful I know a lot of non-vax families-- because otherwise he might not be exposed to some of those things that he should be.

I am glad for you that you live among enlightened folk but I personally don't see how it can make any difference. I know we've been conditioned to believe that when a child is vaccinated that child no longer carries that virus or bacteria. Fact is that the child may or may not be immune to that virus or bacteria but whether that child actually does not carry it is another matter. That pertains to all viruses and bacteria.

Even the polio virus. It's easy to say we have eradicated a particular virus and never really look to see whether people have immunity to it. And when we do see paralysis, we give it a different name. Works every time.

[Marnica]

Not to mention that 95% of polio infections present like the common cold. I bet so many people have actually had poilio and never even knew it since they wouldn't have gone to the doctor and if they did, they weren't tested for polio since they would be told they have a cold!

[Gitti]

I don't believe in herd immunity at all. It just doesn't make sense as OP pointed out.

Herd immunity imo is based on an old theory that believes in good germ / bad germ. But we know for a fact that some pathogens can at times actually be symbiotic bacteria.

It all depends on the milieu.

[Deborah]

And not just the health of the individual body, but the health of the community. Overcrowding, lack of sanitation, lack of fresh air, overwork can all contribute to the conditions which will end in an epidemic.

For example, most families in the developed world have a fair amount of living space. It is quite rare to have children share a bedroom, much less cram 5 or 6 children into one room. But in working class neighborhoods in big cities in the late 1800s it was very common for an entire family to live in one room. Mother, father, several children, sometimes other relatives. If one person gets sick under those conditions, how likely is it that everyone gets sick? Especially if you add in all the other factors.

The vaccines saved us mantra is bs in my opinion. It ignores everything which is well-known about the role of sanitation and improved living conditions and tries to give vaccination all the credit.

[Sileree]

Yup. Even the IOM admitted vaccines saved less lives than sanitation.

[Sileree]

Originally Posted by Gitti

Fact is that the child may or may not be immune to that virus or bacteria but whether that child actually does not carry it is another matter.

That's very true. This is why herd immunity doesn't protect the unvaccinated. Its been demonstrated that measles and mumps can be transmitted even when 95% of the population is immune. It just doesn't work that way in real life. The theory is flawed in that regard.

[ema-adama]

Originally Posted by Sileree

That's very true. This is why herd immunity doesn't protect the unvaccinated. Its been demonstrated that measles and mumps can be transmitted even when 95% of the population is immune. It just doesn't work that way in real life. The theory is flawed in that regard.

Do you have a link for that? That sounds very interesting. (the measles and mumps being transmitted with a 95% immune population.) I would be very curious what percentage of the population was vaccine immune and what percentage was naturally immune - although I am sure that data is not easy to find, if it even exists.

Also, I have been wondering how my children will be able to get the childhood diseases in a highly vaccinated population. I really am much more comfortable with my DC having the diseases when they are children.... I am still looking into this, but are there any mama's here who have personal experience with the childhood diseases in a highly vaccinated population? (I'm talking mumps, measles, rubella, chickenpox)

[Sileree]

Originally Posted by ema-adama

Do you have a link for that?

I don't have a link, but I have titles of studies, google them if you need the authors and journals and such.

"Serological evidence indicates that measles virus could circulate in seropositive, fully protected populations... Although viral transmission between protected individuals has never been directly demonstrated, the data describe a population in which protected but infectious persons could potentially be of epidemiological importance."

["Estimated susceptibility to asymptomatic secondary immune response against measles in late convalescent and vaccinated persons."]

"The overall attack rate is the highest reported to date (and to our knowledge) for a population demonstrating virtually complete mumps vaccine coverage... Vaccination failure may play an important role in contemporary mumps outbreaks. We found no evidence to indicate that waning immunity (secondary vaccine failure) contributed significantly to this outbreak."

["Mumps outbreak in a highly vaccinated school population. Evidence for large-scale vaccination failure.]

"Despite high vaccination levels, explosive measles outbreaks may occur in secondary schools due to 1) airborne measles transmission, 2) high contact rates, 3) inaccurate school vaccination records, or 4) inadequate immunity from vaccinations at younger ages."

["An explosive point-source measles outbreak in a highly vaccinated population. Modes of transmission and risk factors for disease."]

"Outbreaks among school-age persons ranged in size from 5 to 363 cases (median, 25); a median of 60 percent of the cases occurred in vaccinated persons, and a median of only 27 percent of the cases were preventable. The outbreaks among preschool-age children indicate deficiencies in the implementation of the national measles-elimination strategy. However, the extent of measles transmission among highly vaccinated school-age populations suggests that additional strategies, such as selective or mass revaccination, may be necessary to prevent such outbreaks."

["Patterns of transmission in measles outbreaks in the United States, 1985-1986."]

"This outbreak demonstrates that transmission of measles can occur within a school population with a documented immunization level of 100%."

["Measles outbreak among vaccinated high school students--Illinois."]

"The outbreak demonstrated that mumps can sometimes transmit efficiently in highly vaccinated populations."

["Mumps Epidemiology and Immunity: The Anatomy of a Modern Epidemic."]

[Full Heart]

Originally Posted by ema-adama

Also, I have been wondering how my children will be able to get the childhood diseases in a highly vaccinated population. I really am much more comfortable with my DC having the diseases when they are children.... I am still looking into this, but are there any mama's here who have personal experience with the childhood diseases in a highly vaccinated population? (I'm talking mumps, measles, rubella, chickenpox)

Rubella is one that you can have and never realize you have. WC is another. People are probably walking around with it right now and you would never know. They are very mild and very underreported. I am sure there are plenty of mothers out there that think their child has roseolla when its really rubella since they can seem so much alike esp if you don't know the subtle differences.

My brother got the mumps (and was vaxed for it). He was fine. Kid wasn't even sick and we both had to stay home for like 2 weeks. I was so mad lol.

MMR and cp are live virus vaxes so they can shed and therefore cause infection. Since drs are so conditioned to believe that once vaxed you can't get the disease if you present with the same symptoms its often misdiagnosed. So I wouldn't worry too much about not running into these diseases. They are out there and your children might get them and you wouldn't even know it.

[ema-adama]

Sirelee - thank you so much for putting that together for me. I shall be looking into that!

Full Heart - I have been thinking about the whole idea of doctors misdiagnosing and hoping that this will be the way my DC get the childhood diseases. I myself am unvaccinated (other than Hep B that I needed as a student) and had all the childhood diseases. My mothers observation was that vaccinated children also got the diseases, but they took longer to get over them (I am pretty sure doctors would refute this - they say that vaccines make it that any illness is less severe ).

I live in Israel now and the only time I hear about measles in the media is when a group of Ultraorthodox Jews have an 'outbreak' (some Ultraorthodox Jews do not vaccinate their children). Anyway, my brother and I did play dates with sick children in the 80's to catch WC, mumps, measles and chickenpox... not sure how it's done today with no awareness of the illnesses. If push comes to shove I will go and visit friends with unvaccinated children in South Africa

Or are you saying that my DC will get the diseases and I wouldn't even know it? When I had the diseases we knew it.... even WC. I whooped for about 6 weeks I think. Rubella, I have no idea... but measles was a high fever and photosensitivity.

This has turned into a bit of a messy post. I just have been wondering if the MMR is as effective as it is said to be, I have a problem. However, all the posts from Sirelee reassure me somewhat.

[Full Heart]

Most times people don't even know they have rubella. Its such a slight illness. Which is one of the problems with rubella. You can spread it without knowing you have it, infecting women who are pg. WC too you can have and never know therefore infecting the very young babies which can be serious. 5 of my 7 have had it and my oldest ds had a very slight case. I would never have known he had it if the others hadn't had worse cases. When adults get it its often thought to be allergies. It can be very mild. cp too can be very mild, sometimes parents mistakes the spots for insect bites if they don't have many.

I don't think MMR is as effective as it claims to be. CRS actually increased after the introduction of MMR and didn't return to previous levels for years.

[ZoeyZoo]

I hope someone can explain this to me because this is the part of the herd immunity theory which makes not sense to me... if many of the vaxes are not live and do not prevent transmission (i.e.., DTAP, IPV, etc.) then how does this create herd immunity?