Most people already know that it is unusual for someone to get chickenpox twice. That's because the first time you get the infection, your body's immune system is dealing with something it's never seen before, and it takes some time for it to figure out the best way to respond. Once your body has developed a defense, it retains some memory of how to respond in order to counter any future infection attempts by the virus.

The varicella vaccine is a weakened form of the chickenpox virus, and when injected, it triggers an immune response by the body similar to that, which occurs in the naturally acquired "wild type" disease. However, because the vaccine version of the virus is weaker, the immune system is able to overcome it much more readily, and most children don't get sick. Despite the fact that the child avoids all the discomfort, itching and fever that we typically associate with chickenpox, his body still learns enough to be able to guard against any future infections.

A child given the vaccine has a 70 to 80 percent chance of not getting chickenpox at all. The other 20 to 30 percent who do get a "breakthrough" case get a much milder form of the disease. For example, vaccinated children with "breakthrough" chickenpox had an average of 15-30 skin lesions versus 250-500 for "wild type" chicken pox. With regard to chickenpox that could cause complications or hospitalization, there is about a 95 percent protection rate. Side effects of the vaccine are minimal-about 7 percent of children developed a slight rash. Rates for other adverse effects like fever or shingles are the same or lower than for people who didn't get the vaccine. Although it's extremely rare, there is the possibility of transmitting chickenpox to someone else, so people who live with pregnant women or someone who is immuno-deficient should be careful.

It would be a disservice not to mention that there is still some debate, even among pediatricians, as to whether universal immunization of children younger than 13 years old for chickenpox is appropriate. Most objections boil down to three categories: chickenpox is not a severe enough disease to warrant vaccinating everyone; the vaccine may not give the lifelong immunity that "wild type" chickenpox gives; and the vaccine is to expensive and many insurances do not pay for it.

It bears repeating that this debate focuses only on the decision to vaccinate children younger than 13 years of age. Virtually everyone agrees that post-adolescents who have not had chickenpox should be vaccinated, since the disease can be much more severe in older children and adults.

If you have any further questions, talk with your doctor about what is right for your child.

 

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