Thank you for your query,
After scab formation , the risk of getting chickenpox
by the exposed people is rare.
As you got chickenpox during your childhood, there is no risk of getting chickenpox. As the natural disease of chickenpox will give almost 100 percent immunity.
There are chances of your child getting chickenpox if he exposed during the infective period, even though he has been given vaccine
Because the chickenpox vaccine is not 100 percent effective, but it will give protection if the antibiotic titer is high.
Even if the child develops chickenpox it will be mild as there the antibody protection is there.
Hope I have answered your query.