The shingles vaccine is not for everyone

Q You've written about who should get the shingles vaccine, and why. Are there any groups of people who should not get the shingles vaccine?

A: I'm glad you asked because, yes, there are groups of people who should not get the vaccine.

Shingles is a painful skin rash, often with blisters, that lasts from two to four weeks. Its main symptom is pain, which can be quite severe. For some people, the severe pain of shingles continues long after the rash clears up.

Called post-herpetic neuralgia, this condition can last for months, or even years. It can be quite debilitating.

Shingles is caused by the varicella zoster virus (VZV), the same virus that causes chickenpox. VZV quietly remains in your body after you recover from chickenpox, but it can reactivate and cause shingles many years later.

Most adults age 60 years and older should get a vaccine called Zostavax. The vaccine helps prevent shingles - and it decreases the risk of post-herpetic neuralgia if shingles does occur. The vaccine is also approved for people 50 and over.

People generally should get the shingles vaccine even if they have already had shingles: The vaccine will reduce the risk of getting shingles again.

The shingles vaccine consists of actual living varicella zoster virus that has been greatly weakened. The weakened virus stimulates the immune system the same way infection with the regular virus would. However, the virus has been so weakened that it cannot cause problems in people with healthy immune systems.

Still, some people should not get the shingles vaccine or should wait. This includes:

• Anyone who has had a severe allergic reaction to gelatin, the antibiotic neomycin, or any other component of the shingles vaccine. Tell your doctor if you have any severe allergies.

• A woman who is pregnant, or might be pregnant. Women should not become pregnant until at least four weeks after getting the shingles vaccine. That's because pregnant women have a somewhat weakened immune system.

• Anyone with a moderate or severe illness (including a temperature of 101.3 degrees F or higher) should wait until they recover before getting the vaccine. The vaccine is less effective when given to someone who is sick with another infection.

• A person who has a weakened immune system, and therefore might be made sick by the virus in the vaccine. People with weakened immune systems include those: with HIV/AIDS or another disease that affects the immune system; receiving treatment with drugs that affect the immune system (for example, prolonged use of high-dose steroids); receiving cancer treatment such as radiation or chemotherapy; who have cancer affecting the bone marrow or lymphatic system, such as leukemia or lymphoma.

Shingles is no fun - and post-herpetic neuralgia can be very debilitating.

So the shingles vaccine has been a very good thing for most people, but not for all.

• Dr. Komaroff is a physician and professor at Harvard Medical School. For questions, go to AskDoctorK.com.