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March 15, 2005
Chicken pox herd immunity
Slate has an article about the chickenpox vaccine. Here's the really interesting part:But now the questionable durability of the immunity produced by the vaccine may alter the cost-benefit calculus. Older studies have shown that immunity to chickenpox (which historically has been virtually perfect after an attack of the virus) seems to depend on re-exposure. Those findings have been borne out in Japan, where some kids are immunized against chickenpox and others are not. It turns out that the vaccinated kids keep up high levels of protection because they are exposed over and over again to unprotected kids who catch the disease and pass it on. Each time such an exposure occurs, the immunized kids get a little "boost," which stimulates their immunity. Doctors think that the same thing happens to older patients who are at risk of shingles because they once had chickenpoxevery time they're exposed to poxy youngsters, their immunity gets a kick, which helps to suppress the reactivation of the latent virus as shingles.
One of the advantages of the Sabin Oral Polio Vaccine (OPV) is that recently immunized patients shed the attenuated virus and this can stimulate immunity in people who haven't been vaccinated. This is sort of the opposite case: non-immunized people can improve the immunity of the vaccinated.
Posted by ekr at March 15, 2005 9:46 PM | Filed under:
Comments
My understanding is that many vaccinations (DPT for example) depend on a certain percentage of the population not getting the vaccination. There is a story I've heard of a child having pertusis that was misdiagnosed because he had been vaccinated for it. But the vaccinations were so pervasive that the virus was no longer in the wild.
A long time ago (twenty some years) my wife and I studied the vaccination scene and decided not to vaccinate our infant daughter. No ill effects; she is happy and healthy today. She did choose to get some vaccinations when she was older and she follows standard vaccination procedures with her kids.
It's hard not to be cynical and see the drug companies as the major beneficiaries of vaccinations.
Nice blog. I like the mix of topics. Can we see a picture of you in the Beyondfleece jacket?
Posted by: Peter Fleck at March 19, 2005 8:26 AM
Well, it's certainly true that with certain vaccines (oral polio is the standard example) there's an equilibrium point after which most infections are caused by the vaccine. However, I don't think most vaccinations *depend* on there being disease in the wild, and most of the vaccines (e.g. influenza) have no major risk of converting to an infectious form.
I don't think it's really true that drug companies are the major beneficiaries of vaccines. Indeed, my general sense is that vaccines are underprovided by the market. Certainly, when I'm offered the chance to get vaccinated against something I might reasonably expect to get (flu, tetanus, hep B (I do a lot of martial arts), etc.) I generally take it.
Posted by: EKR at March 19, 2005 8:49 AM