When She Will Get Chicken Pox Will My Niece Get The Chicken Pox?

Will my niece get the chicken pox? - when she will get chicken pox

My niece had her first birthday last Saturday and had several cousins in your group. One of the cousins was beautiful that day, but on Sunday came with chickenpox. My niece had shot no chicken pox, but remember, you get chickenpox? If indeed occur when the first symptoms, and what are the symptoms? Thanks