Rash and Herpes Zoster After Vaccination. Rash from varicella vaccine is usually mild. The risk of spreading varicella from this rash appears to be very low. After a person is vaccinated, they can get infected with wild-type varicella-zoster virus (VZV).This is called breakthrough varicella. It is usually mild, but it is still contagious.ash from varicella vaccine is usually mild. The risk of spreading varicella from this rash appears to be very low. After a person is vaccinated, they can get infected with wild-type varicella-zoster virus (VZV).