You may think that chickenpox is a harmless disease, so why bother having a vaccine for it? Chickenpox is relatively benign. The vast majority of children with chickenpox recover from it with just a few barely visible scars on the body. However, a small percentage of children may suffer serious complications from the chickenpox infection. Even though the chance of having a serious problem with chickenpox is so small, this group of people may add up to a sizable number since chickenpox is so common. Before the chickenpox vaccine became available, almost every single child got the chickenpox before reaching adulthood.

To prevent the 10,000 hospitalizations and few cases of death each year, the chickenpox vaccine was licensed in 1995. Initially, only a single dose of this vaccine was recommended for children twelve months or older. However, the chickenpox vaccine was only 85 percent effective in preventing chickenpox if only one dose was given. Currently two doses of the chickenpox vaccine are recommended. The first dose is usually given at the one-year visit, and the second dose is routinely scheduled at the four-year visit. Adolescents who only had a single dose when they were younger can get the booster dose at any time as long as it has been more than four weeks after their first chickenpox shot.

Aside from some people questioning the necessity of the vaccine, another aspect of the chickenpox vaccine that makes it more controversial is that contains live chickenpox virus. When your child receives the vaccine, she in effect gets a very mild case of chickenpox. For most children, the symptoms are so mild that they are not even noticeable. About 5 percent of children who receive the chickenpox vaccine can have a fever and rash after vaccination. However, this mild form of chickenpox never causes complications such as pneumonia or death. Usually the rash is so mild that it may be confused with bug bites.

The chickenpox vaccine can be combined with the MMR vaccine as a four-in-one injection. The pharmaceutical company Merck has made this combination vaccine (often referred to as the MMRV vaccine) available since 2005. However, there was a nationwide shortage of this combination vaccine in 2008, and the shortage is ongoing at the time this book was published.

If the chickenpox vaccine is not given at the same time as the MMR vaccine, these two vaccines must be spaced at least twenty-eight days apart. Since both of these vaccines contain live viruses, they can interfere with each other if they are given too close together (unless they are given simultaneously).