Chicken pox vaccine not very effective

Andy sends this Reuters story:

During an outbreak of chickenpox in Minnesota in the fall of 2002, more than half the children who became infected had been immunized with the varicella vaccine, according to a new report.

Evidently, booster shots may be required to provide stronger protection against chickenpox. ...

The primary case in the outbreak was a vaccinated 6-year-old boy. ...

Lee's group estimates that the effectiveness of the vaccine in warding off infection was 56 percent.

The chicken pox vaccine was sold to the public as a vaccine that would not need a booster, and most states have made it mandatory for the schools.