“How effective is the chickenpox vaccine?”

Of course, each individual's immune system is unique and may respond to infections/vaccines in a unique way. That being said, the first dose of Varicella (chicken pox) vaccine confers about a 75% immunity -- after two doses, there is about a 97% immunity. That means that out of 100 people who have been vaccinated and then exposed to chickenpox, 97 of them would be immune and 3 would get the illness. Since the availability of the varicella vaccine, becoming immune through natural infection has become less and less likely, but chicken pox has not been eradicated from either the US or the world. That means that you can still catch it. Having chicken pox as a child is usually not a life-threatening condition, although it can be in certain circumstances. However, chicken pox as an adult is a much more serious condition. If you do not have chicken pox as a child, and you do not get vaccinated, as an adult you are at risk for the illness, which could be very dangerous. The best way to protect your child, both as a child and as an adult, is to vaccinate with two doses. Note that the varicella vaccine is a "live virus vaccine," which means that individuals with certain conditions can NOT get it, and cannot be exposed to individuals who have recently received the vaccine. Be sure to check with your pediatrician to get all the facts.

Shelley C. Springer, MD, MBA, MSc, JD, FAAP