This article originally appeared in the August 2005 Harvard Health Letter and is provided courtesy of
Harvard Health Publications.

These shots aren’t just kid stuff

Adults may soon be rolling up their sleeves to get vaccinated for shingles and whooping cough.

Chickenpox and whooping cough are just childhood diseases, aren’t they? Would that it were so.

The varicella-zoster virus that causes chickenpox in children re-emerges in adulthood to cause the condition called herpes zoster — more commonly known as shingles. As for whooping cough, even some doctors view it as a kids-only affliction. But a growing proportion of cases occur in teenagers and adults.

Both diseases are difficult to treat, partly because they must be caught early if treatment is to work at all. That makes prevention with vaccines especially attractive. Today children are vaccinated against both whooping cough and chickenpox.

It’s harder to devise vaccines for adults who have lost their immunity or were never vaccinated in childhood. But positive results for a shingles vaccine for adults were published in the New England Journal of Medicine in early June 2005. Several weeks later, different investigators reported favorable results for a whooping cough vaccine in the Journal of the American Medical Association (JAMA). There are regulatory and other hurdles ahead, but maybe as soon as 2006 we grown-ups will be joining the kids and getting vaccinated against varicella and whooping cough.

It’s hard to keep a bad virus down
By some estimates, 50% of those who live to age 85 will experience a case of shingles. By some estimates, every year one million Americans come down with a case. That number is likely to grow as baby boomers get older, because shingles mainly affects those 50 and older.

The classic symptoms are a bad rash consisting of clusters of blisters and red areas, along with pain in the same place as the rash. Usually the rash and pain are limited to one area, either on the face, legs, chest, or abdomen.

The initial symptoms are bad enough. But some people go on to develop postherpetic neuralgia — pain that persists or starts after the rash has gone away. Some people have it for a year or longer. The chances of developing postherpetic neuralgia increase with age. Early intervention with antiviral medications can reduce the severity of the blistery rash but doesn’t seem to prevent postherpetic neuralgia.

Shingles is caused by the varicella-zoster virus, which was discovered over 40 years ago at Harvard Medical School. The virus infects many people in childhood, causing chickenpox, although a small percentage of children become infected but never develop the disease.

Once infected, a person stays that way. The varicella virus has the ability to hide out in nerve cells and be dormant there for decades. Interestingly, antibody levels against varicella stay high after chickenpox. But other parts of our immune system (namely, T cells) start to weaken as we get older. Varicella seems to enjoy its second act as misery-producing shingles because our immune systems flag and can no longer keep it holed up.

Promising study results
The study in the June 2, 2005, New England Journal of Medicine included more than 38,000 people ages 60 and over. Half received the experimental vaccine developed by Merck, which helped pay for the study that was run by the Department of Veterans Affairs; the other half were given a placebo. During three years of follow-up, those taking the vaccine were half as likely to develop shingles (315 cases versus 642) and, better yet, two-thirds less likely to develop postherpetic neuralgia (27 cases versus 80). Only 2 of the 19,270 people who were vaccinated had a serious adverse reaction, which is remarkable, given that the vaccine used in this study is 14 times more potent than the childhood vaccine against chickenpox.

Merck filed an application for FDA approval in April 2005, so the vaccine could be available in spring 2006. Cost-benefit analyses suggest that it will be worthwhile, even though shingles isn’t fatal and doesn’t ordinarily require hospitalization. The vaccine will be for older people with healthy immune systems who have had chickenpox, (you can only get shingles if you’ve had chickenpox, and most adults have) but haven’t already had shingles. Recurrent cases of shingles are rare, so if you’ve had a case, the vaccine won ’t be necessary.

Pertussis is coming back
Pertussis is known as whooping cough because the classic symptom is a series of rapid coughs, followed by a gasp for air that makes a high-pitched, ascending “whoop.”

Before a vaccine became available in the 1940s, pertussis was responsible for more than a quarter of a million serious illnesses a year and about 10,000 deaths. But the vaccination campaign was a big success, and it seemed like pertussis was disappearing. In 1976, the number of reported cases hit a historical low of 1,010 for the entire country.

Since then whooping cough has made a comeback. In 2004, according to a preliminary federal government count, there were almost 19,000 cases. There’s some speculation that the number of cases has skyrocketed because weaker vaccines were used to avoid side effects, according to Dr. Michael E. Pichichero, a University of Rochester researcher and lead author of the JAMA study. The thinking, he says, is that vaccine makers weakened the vaccine because they were worried about lawsuits, although the companies have strongly denied any such changes were made. Dr. Pichichero says part of the increase may also be a matter of better testing and better diagnosis by doctors.

The early pertussis vaccines were made from whole bacteria that had been killed. They were great for boosting immunity, but they occasionally caused high fever or seizures, so in 1996, an “acellular” vaccine was licensed. This version has fewer side effects because it uses just parts of the bacterium.

No big whoop
According to current guidelines, children are supposed to get a series of five pertussis shots before turning six (the vaccine is given in combination with vaccines for diphtheria and tetanus).

But immunity only lasts for about 10 years, so adults can come down with the disease. In the United States, about a fifth of reported cases occur in people over age 20 — and by no means are all adult cases reported. That’s partly because in teenagers and adults, particularly those who’ve been vaccinated, the infection may cause a cough without the signature whoop. This whoopless whooping cough is easily confused with run-of-the-mill upper respiratory infections. Studies have found that up to a third of persistent coughs in teenagers and adults are likely caused by undiagnosed pertussis. A further complication is the difficulty of identifying Bordetella pertussis, the bacterium that causes the disease.

In rare instances, pertussis can cause pneumonia or seizures, but these days it’s hardly ever fatal. In fact, the infection can be so mild in adults that it doesn’t even produce a cough. But when it does, the cough can last a long time — in one out of four adult cases, for three months or more. Antibiotics help limit the duration and severity of the infection and may keep it from spreading to others. A 14-day course of erythromycin is often recommended, although azithromycin (Zithromax) taken for five days may be just as effective. People in close contact with someone who is infected are often given antibiotics as a preventive measure. Still, there’s some debate about how effective the antibiotics are, especially if they’re not started within a week after symptoms appear.

The company-sponsored study published in JAMA in June 2005 showed that an experimental shot combining vaccines for diphtheria, tetanus, and pertussis produced a strong immune response. Dr. Pichichero said the pertussis component of the vaccine was a fourth as strong as the pediatric version. It can be weaker because the immune system has already been primed by pediatric inoculations, he said.

Teens first
Cost-benefit research has found that targeting teenagers for pertussis vaccination makes the most sense. American teenagers are already supposed to get a diphtheria and tetanus booster, so adding some pertussis vaccine to that shot won’t be a major inconvenience. The FDA approved a new pertussis booster shot specifically for teens in May 2005 and then approved a different version for 11- to 64-year-olds in June 2005. Both were approved as part of a combination that included diphtheria and tetanus boosters.

But FDA approval is separate from federal vaccine guidelines, which come out of the Centers for Disease Control and Prevention. As of June 2005, the guidelines hadn’t been revised. One possibility under discussion: A recommendation that all teens would get one of the new pertussis-diphtheria-tetanus shots, but only certain groups of adults would, such as health care workers and women of childbearing age.

Will other adults be able to get the new pertussis booster? Probably, but whether your insurance will cover the cost may depend on the federal vaccine guidelines. If you pay for it yourself, it should cost you about $35, exclusive of doctor and other fees.