The chicken pox vaccine is extremely effective in keeping kids from getting chicken pox.
However, a small number of people who get the vaccine still come down with the illness.
Chicken pox is caused by a contagious virus and is associated with an itchy blister like skin rash that covers the body.
Most children get a chicken pox vaccine as part of their routine immunization. But some people who have been vaccinated still end up getting the disease.
"There are trends across the country and they've been documented across the state as well that there is a 20 percent chance," explains Christine Connolly, Arlington Board of Health.
It is called breakthrough chicken pox. Health experts say these individuals will usually get a mild case of the disease with fewer spots and will recover faster.
So why does this happen in the first place?
"They’re continuously researching that and there are other options available," says Connolly.
The bottom line when it comes to the chicken pox vaccine and immunization shots in general.
"The message continues with vaccinations. I think that's the main point that we would like to get across," explains Connolly.
The centers for disease control recommend that children over a year-old get vaccinated for chicken pox.