Kids who have had the Chicken Pox Vaccine might need a booster shot.
The U.S. Centers for Disease Control and Prevention have found that while the vaccine has significantly cut down on the number of itchy Chicken Pox cases.
It can also lose its effectiveness over time.
A CDC Committee has recommended kids get a second shot around ages 4 to 6, but it is unclear how long that shot would last.
The vaccine is shown to be effective in about 80% to 85% of children.
A booster shot could raise that percentage to about 90% to 95%.