A primer on chickenpox
The virus spreads primarily through direct contact with an infected individual, such as sneezing and coughing. The infectious period begins up to five days prior to onset of the rash.
Shingles is a latent form of the virus. If you have immunity to chickenpox, an outbreak will not increase your chances of having the dormant shingles virus flare up in your system.
You have immunity to chickenpox, according to the Centers for Disease Control, if you meet one of the following criteria.
You have documentation of age-appropriate vaccination, which is one dose for children from 1-to-5-years old and two doses for all others.
If you were born in the United States before 1980. Most people were exposed to the virus; exposure creates immunity even without visible symptoms. However, health-care personnel, pregnant women, and people with compromised immune systems should still check with a doctor about immune status.
You received a clinical blood test showing immunity.
If you have had chickenpox or shingles. It is rare to get the virus twice.
If you are at all uncertain of your immunity status please contact the Fermilab Medical Office at firstname.lastname@example.org or X3232 as well as your personal doctor. There are measures that can reduce the likelihood and/or severity of the developing virus.
To learn more, view this pdf from the Illinois Department of Health.