DEAR DR. ROACH: Have you ever heard of a fully vaccinated 79-year-old woman getting a repeat case of shingles? This is actually my fourth time having it. My first occurrence of shingles was when I was 26 years old, and it was on my torso. The next two occurrences were on my forehead, and I got antiviral medication for them. They subsided rather quickly, although I was left with some neurological aftereffects.

When the first vaccine came out several years ago, I received it. Then as soon as Shingrix was available, I got both of these shots. This time, I’m on antiviral medication and hoping for a mild case. I do have other possible immune-system-related conditions, including vitiligo, seborrhea, angular cheilitis and interstitial cystitis.

— D.

ANSWER: Chicken pox is a viral illness that is caused by one of the viruses in the herpes family. Shingles is a reactivation of the chicken pox virus in a specific area of the body. Getting shingles a second time is unusual but not unheard of; however, there are very few instances of shingles coming back three or more times.

The first thing I want to be sure of is whether it really is shingles, meaning that the lab should positively identify a sample of one of the lesions as varicella-zoster virus, which causes both chicken pox and shingles. Herpes simplex virus (which causes cold sores) can look a great deal like VZV, and it is sometimes mistaken for shingles. The occurrences on your forehead might have actually been HSV, not VZV.

If it is proven to be recurrent shingles, your doctor should look for something wrong with your immune system. The conditions that you mentioned, especially vitiligo, are often associated with an immune system that reacts against itself, like with an autoimmune disease. People who get recurring viral infections should be suspected of having a “hole” in their immune system, called an immunodeficiency.

By far, the most common immunodeficiency that is associated with recurrent shingles is an HIV infection, so you should also get an HIV test. I do see HIV in people in their 60s and 70s. I don’t wish to alarm you with the thought of HIV, but I also have to tell you that an unsuspected cancer can also predispose you to the recurrence of shingles, as cancer can suppress the immune system.

There are rare primary immunodeficiencies (ones people are born with) that can predispose people to recurrent herpes viruses. These are out of the expertise of most primary care doctors, so an immunologist would be the expert to consult.