The Link Between Chickenpox and Shingles

Just before Christmas a few years ago, Richard DiCarlo, MD, woke up in the night with burning pain on his left side. Turning on a light, he saw a row of red bumps and knew immediately that he had shingles, also known as zoster, caused by the reactivation of the chickenpox virus, dormant since a childhood infection.

After shingles and a year of postherpetic neuralgia, a painful condition that made it difficult to sleep, DiCarlo, an infectious disease specialist at Louisiana State University in New Orleans, counts himself among the supporters of the shingles vaccine. The shingles vaccine Zostavax was licensed in the U.S. in 2006. Data from the Shingles Prevention Trial, which enrolled 38,000 adults aged 60 and over, showed that men and women who got the shingles vaccine were half as likely to get the ailment after an average follow-up period of three years compared to those given a placebo shot. Vaccinated study participants who did develop shingles also had reduced pain compared to participants given a placebo shot. The vaccine was most effective in people ages 60-69 with increased decline in effectiveness associated with older age.

Research begun in the 1950s has shown that when we recover from childhood chickenpox infections, the virus that causes the infection, varicella zoster virus, remains latent in nerve cells.

What causes reactivation of the virus is unclear, but as we age, experts believe the immune responses that keep varicella zoster virus dormant in the nerves weaken with age. One in three people will get shingles during their lifetime, and at least half of all people 85 and older have had the ailment.

When you get a shingles rash, it typically involves a particular “dermatome,” that is, the skin area supplied by the involved nerve usually on one side of the body or face. However, in some cases the shingles rash can be widespread. Before the rash appears, people may have nerve symptoms of pain, itching, burning, or tingling. The rash has blisters that scab over in about a week. Although shingles isn’t contagious, the virus can spread to others and can cause chickenpox.

In DiCarlo’s case, the shingles involved the left side of his torso, in a band from the spine to the belly button.

Antiviral drugs can be used to lessen the severity and duration of shingles, but effectiveness is dependent on using it as soon as possible. Pain medicines and other remedies may be used to help treat symptoms.

Up to one in five people who get shingles suffer from postherpetic neuralgia, usually defined as zoster-related pain that occurs in the area of the shingles rash even after the rash is gone. It can last for a few weeks, months, or longer. The older you are when you have zoster, the more at risk of developing postherpetic neuralgia.

“A lot of people get shingles and it’s relatively minor or moderate pain, and they get over it in a week. If that were the only risk, I would wonder about the overall usefulness of the vaccine,” DiCarlo said. “But I have to say, if you can reduce getting postherpetic neuralgia by 65-70 percent, it’s worth it. You don’t want to go through that.”

The FDA approved the vaccine as a one-time dose for people 50 and over. As noted, the rate of shingles increases with age. Medicare part D covers the shingles vaccine, but your contribution to the cost may vary. Private insurance plans or Medicaid may not cover payment for the vaccine. You will need to check with your insurance company about coverage.

What if you have never had chickenpox or have already had a case of shingles? You should still get vaccinated because studies show that nearly all adults 40 years and older have had chickenpox whether they remember having it or not. Also, if you’ve already had shingles, the vaccine can help protect against recurrence.

The vaccine is not safe for all people. People who should NOT get the vaccine include:

• People who have ever had a life-threatening reaction to or are severely allergic to gelatin, neomycin, or any component of the shingles vaccine.
• People with a weakened immune system from certain medical conditions or treatments.
• Pregnant women or those who may be pregnant

The most common side effects reported with getting the vaccine include redness, soreness, swelling or itching at the injection site, and headache. Some people may develop a rash at the injection site that looks like chickenpox.

As we age, we become more susceptible to shingles, and people who are immune-suppressed, such as people with cancer or HIV, are also at higher risk of the disease. But other hypothesized triggers, such as stress or sunburn, remain unproven, says Stephanie R. Bialek, MD, MPH, leader of the herpes virus unit at the CDC’s Division of Viral Diseases.

A study by the CDC and other scientists confirmed that since 1993, the incidence of shingles has nearly doubled in the adult U.S. population. One explanation for the increase has to do with the universal vaccination of children against chickenpox. According to this theory, because most children no longer get chickenpox disease (which used to be a ritual of childhood), their parents no longer get the immunological “boost” that comes from being exposed to the virus while caring for sick children.

“The best explanation for the increase is that we used to get a subclinical boost when we were exposed to the chickenpox virus as adults,” said William Schaffner, MD, a pediatrician and vaccine expert at Vanderbilt University. “Because of widespread immunization, that’s not happening.”

But there are some reasons to doubt that childhood chickenpox shots are responsible for the uptick in shingles. In their study, Bialek and colleagues found that shingles was on the rise even before the chickenpox vaccine was licensed for children in 1995. Also, adults in states with mandatory chickenpox immunization didn’t have higher rates of shingles than those in states where children weren’t as well-vaccinated, and therefore more likely to get sick and provide immune boosters to parents and grandparents.

It’s possible that as the U.S. population is getting older, more people are seeing their doctors for shingles. “There are probably different factors involved in the increase,” says Bialek. And it may take decades to sort it out. But regardless of whether shots against chickenpox increased the risk of shingles, the shot against shingles is the best way to avoid it.