Roughly one in five people who've contracted chicken pox, or varicella, will eventually have a bout of shingles, though no one knows precisely why the virus resurrects. The condition, also known as herpes zoster, commonly plagues transplant patients during the year following the procedure, as well as other people with suppressed immune systems.

The new study by Stanford University researchers found that bone marrow recipients immunized with varicella vaccine were far less likely to suffer a recurrence of the viral infection in the year after the graft as those who weren't vaccinated.

Zoster initially strikes the nerve endings at the skin, leading to severe pain and a rash. However, in people with weakened immunity the virus can afflict internal organs, too.

Although shingles could potentially be fatal for these patients, it's "at the very least miserable," says Dr. Karl Beutner, a skin specialist at the University of California at San Francisco. That boosting immunity helps prevent shingles supports the hypothesis that the virus remains dormant in the nervous system and awakens when the body's defenses falter, Beutner adds.

A report on the findings appears in tomorrow's issue of the New England Journal of Medicine.

Dr. Ann Arvin, a Stanford infection expert, and her colleagues sought to learn if giving bone marrow recipients the chicken pox vaccine might prevent shingles flare-ups.

The varicella vaccine offered to children is a live, weakened virus that offers near-complete protection against chicken pox when timed appropriately. Because of the risk to transplant patients of using a live pathogen, Arvin's group had to obtain a heat-treated version of the injection.

The researchers gave the vaccine to 53 patients 30 days before the transplant, and again at 30, 60 and 90 days after the procedure. Seven (13 percent) went on to develop shingles, compared with 19 of 56 patients (30 percent) who weren't inoculated.

Patients who received the shots had stronger immune responses to varicella virus, and the strength of the reaction increased with the number of injections. People with the highest immune cell response had 93 percent protection from shingles.

The vaccine caused generally mild side effects 10 percent of the time. These included hardening of the skin, redness and pain at the site of the injection.

Dr. Aaron Rapoport, a University of Maryland cancer researcher, says the new study has important implications for controlling other infections in transplant patients.

"It's a demonstration that a vaccine may help to reduce the occurrence of infections during the post-transplant period, and there are other infections that one can potentially address in that way," he says.

Rapoport is now conducting a study in bone marrow graft recipients with multiple myeloma using a vaccine against Pneumococcus, a leading bacterial cause of pneumonia.

What To Do

For more on shingles, try the American Academy of Dermatology or the Centers for Disease Control and Prevention.