I've come to the conclusion that, now that we've started vaccinating for varicella, we have to continue, even if the vaccine itself isn't that good as vaccines go.
The reason: the first effect of a vaccine is not to eliminate the disease from the population, but to raise the average age of infection into the ranks of those not yet vaccinated. So if the average age of infection before the vaccine was five or six, five years after the introduction of the vaccine, the average age will have risen by seven or eight years (depending on the prevalence of the disease in the population, it will go up higher than just the age difference, because there will be fewer vectors of infection running around.) If vaccination continues so that most babies are vaccinated, then the average age of infection factored into the decreased incidence of the disease effectively eliminates the disease for all but a few people, possibly all of them, and herd immunity is achieved.
The problem comes if vaccine uptake is incomplete. A study was done on the vaccine for rubella in Greece, where it was not mandatory and uptake was slow during the eighties. The study found that, when only 50% of the population was vaccinated, the effect was to keep just enough disease vectors in the population that the average age of infection settled on the early twenties. Rubella is most dangerous to pregnant women and their babies, so there was rash of brain-damaged babies due to measles infection in Greece throughout the decade.
This ceases to be a problem if the people who refuse to vaccinate their babies against varicella are willing to either ensure that they get chicken pox naturally, or get them the vaccine later if they don't catch it by a certain age. But the result of incomplete immunity would end up being worse than no vaccine at all.
This argument has particular force in the case of varicella/chickenpox because the disease is so much more serious in adults and older children than in young children. The vaccine is much more necessary for people who have not caught the disease in early childhood than it is for young children; however, with most kids being vaccinated, non-vaccinated kids aren't necessarily going to catch it in early childhood when it's relatively safe.
This would also have been a good reason not to vaccinate at all, of course; if we'd developed the vaccine mostly to increase the immunity of those who are at risk later in life, but had left the kids alone, we'd be in better shape.
I have no problem with anyone who chooses to delay the chicken pox vaccination until later. I didn't do it in part because of my friends' daughter's experience (catching chicken pox around the same time she was admitted to Sick Kids for something life-threatening at the age of 20 months.) But then, I have never come across a kid who has significant adverse reactions to vaccines, much less had such a child in my family.
This is where I agree with you. What bothers me is that I think the vaccine wasn't sufficiently studied before mass vaccination took place, and now what we're seeing is LOTS of adults my parents' age getting shingles. My doctor said they now suspect that the "immunity" we all thought we had to varicella depended on boosters in the form of exposure to little kids who had the disease; now that they're not getting it, those boosters are going away.
We're planning on having the girls catch chicken pox-- I don't know if naturally is the right word, because we're going to actively ensure that they get it when it's going around next. We waited until Caroline was verbal so we can keep her from scratching.
As the child of a polio survivor who suffered permanent spine and leg damage as a infant, (and now has PPS) thank you for sharing this. As someone who follows most of the standards of attachment parenting, but does vaccinate (selectively/delayed with my oldest, and on schedule with my youngest) I find myself constantly defending my choices to other parents at LLL or babywearing meetings. Maybe I'll just direct them to this episode in future after I view it in it's entirety.
I've found the Penn & Teller episode on circumcision to be especially effective in preventing it for friends expecting baby boys. Something about the way they present things really gets to viewers. I've never seen this episode before however...
My view on circumcision is that it's something a man should be able to choose for himself when he's grown up. The evidence is strong that it reduces the likelihood of contracting HIV, but condoms do that pretty effectively on their own. So I think it should be up to the guy to choose once he is capable, although I wouldn't blame a mother in a country with high rates of HIV and low rates of condom use for circumcising her son. .
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(no subject)
Date: 2010-11-21 09:05 pm (UTC)(no subject)
Date: 2010-11-21 09:29 pm (UTC)The reason: the first effect of a vaccine is not to eliminate the disease from the population, but to raise the average age of infection into the ranks of those not yet vaccinated. So if the average age of infection before the vaccine was five or six, five years after the introduction of the vaccine, the average age will have risen by seven or eight years (depending on the prevalence of the disease in the population, it will go up higher than just the age difference, because there will be fewer vectors of infection running around.) If vaccination continues so that most babies are vaccinated, then the average age of infection factored into the decreased incidence of the disease effectively eliminates the disease for all but a few people, possibly all of them, and herd immunity is achieved.
The problem comes if vaccine uptake is incomplete. A study was done on the vaccine for rubella in Greece, where it was not mandatory and uptake was slow during the eighties. The study found that, when only 50% of the population was vaccinated, the effect was to keep just enough disease vectors in the population that the average age of infection settled on the early twenties. Rubella is most dangerous to pregnant women and their babies, so there was rash of brain-damaged babies due to measles infection in Greece throughout the decade.
This ceases to be a problem if the people who refuse to vaccinate their babies against varicella are willing to either ensure that they get chicken pox naturally, or get them the vaccine later if they don't catch it by a certain age. But the result of incomplete immunity would end up being worse than no vaccine at all.
(no subject)
Date: 2010-11-21 09:40 pm (UTC)(no subject)
Date: 2010-11-21 09:44 pm (UTC)I have no problem with anyone who chooses to delay the chicken pox vaccination until later. I didn't do it in part because of my friends' daughter's experience (catching chicken pox around the same time she was admitted to Sick Kids for something life-threatening at the age of 20 months.) But then, I have never come across a kid who has significant adverse reactions to vaccines, much less had such a child in my family.
(no subject)
Date: 2010-11-21 09:46 pm (UTC)(no subject)
Date: 2010-11-21 10:15 pm (UTC)We're planning on having the girls catch chicken pox-- I don't know if naturally is the right word, because we're going to actively ensure that they get it when it's going around next. We waited until Caroline was verbal so we can keep her from scratching.
(no subject)
Date: 2010-11-22 12:29 am (UTC)(no subject)
Date: 2010-11-21 09:43 pm (UTC)(no subject)
Date: 2010-11-21 09:48 pm (UTC)(no subject)
Date: 2010-11-21 10:27 pm (UTC)I've found the Penn & Teller episode on circumcision to be especially effective in preventing it for friends expecting baby boys. Something about the way they present things really gets to viewers. I've never seen this episode before however...
(no subject)
Date: 2010-11-21 11:38 pm (UTC)