Can you believe it? She was immunised when she was three and a half. She had chicken pox when she was four and a half and now again when she is six and a half. What's going on?
The first time she had chicken pox it didn't really concern me that much. It was an extremely mild case anyway. It does concern me now that she has it again. It seems that the vaccine has not only not protected her from the disease but has also prevented her developing natural immunity. That's what concerns me.
Both times have been very mild manifestations of the disease. This makes me think that perhaps it doesn't matter so much if she has repeated cases. But, if she is infectious and can pass on the disease to others, then it does matter. Besides which, the poor thing is very itchy!
So what's going on? I don't know. The immune system is amazingly complicated and clever. So are viruses. I know a very little about viruses, and even less about immunology. But I think there are three possibilities.
- The vaccine worked but one or both cases have been misdiagnosed. This is unlikely as both cases have been verified by a GP. This time, the doctor took a swab* to test for DNA from the varicella virus which cases chicken pox.
- The vaccine didn't work at all (out of date or mishandled in some way), and she has been unfortunate to have had two cases of chicken pox. This is not unheard of.
- The vaccine is working in as much as it prevents serious manifestations of the disease. Unfortunately, this seems to mean that natural immunity has not been acquired.
Can you think of other possibilities? Have you heard of other, similar cases? Can someone recommend a good (simple) text on immunology? Does any one know how the chicken pox vaccine, in particular, works?
*Interestingly, when taking a swab, the intent is to take the fluid from inside the blisters, only there didn't seem to be much of it. Not sure how significant this is.