How can i prevent infecting my 1yr 3mo old baby and pregnant sister staying with me from chicken pox. i just got infected. baby has been vaccinated?

Difficult: if baby has been vaccinated then s/he most likely is immune. Spread is through touching and kissing and unfortunately, coughing. Your sister if in the third trimester does not have much to be concerned about. Rarely, a woman in the first or second trimester may spread the disease to the fetus, which can cause severe effects. Suggest your sister I have an antibody test to see if she is at risk