I Did Not Have Chicken Pox Why Did My 4 Year Old Get Chicken Pox If He Was Vaccinated?

Why did my 4 year old get chicken pox if he was vaccinated? - i did not have chicken pox

The doctor said he seems to start a serious matter, and that essentially quarintine him (as Dr. 's Office).

Without mentioning anyone has in this area has recently had chickenpox, so now I wonder where he got it.