A QUESTION OF IMMUNITY; Vaccines work wonders against deadly diseases, but some parents want to know: Are they safe for everyone?

THE BALTIMORE SUN

Diphtheria, polio, whooping cough: They're diseases of long ago. In the current spate of summaries of 20th-century news, we see old photographs of grieving parents, and long wards filled with iron beds and suffering children. But the next picture is likely to be a line of children waiting to get the new vaccine, and smiling parents.

Most people now take vaccines for granted. They got their shots, their children get their shots, and the shots work. The fatal epidemics of the past don't happen anymore. The last reported case of diphtheria in Maryland was in 1973. There was one case of measles last year; no polio.

But Dr. Neal Halsey, director of the Institute for Vaccine Safety at the Johns Hopkins School of Public Health, has seen what such diseases do. "The organisms that cause these diseases still exist in this country," he says. "If people stopped getting immunized, no question we'd have recurrences. "Young parents haven't seen [the diseases], so they no longer have the fear. But for people like myself who've seen children suffer and die from these diseases, there's no question: We must immunize."

But increasingly vocal groups of parents and others have a different view. They don't see the damage of the diseases, but they're too familiar with injuries caused by, or believed to be caused by, vaccines. More and more often, they're taking their cause to Congress and the media.

The most visible of these is Barbara Loe Fisher of Vienna, Va., who believes her son's learning disabilities were caused by a vaccine reaction. She has become an activist, founding the National Vaccine Information Center and co-writing the book "A Shot in the Dark," about issues around the DPT vaccine.

"Parents are instinctively starting to question why children need all these vaccines. I'm not saying parents don't want to vaccinate -- most want to, but they want to do it safely. They want flexibility on timing and on the number of vaccines," Fisher says.

"Before we add more vaccines into this mix we have to do scientific research into this and find out whether there are dangers. The breach of trust occurring here on this issue threatens trust in all of health care."

Like Fisher, many groups are careful to say they are not "anti-vaccine" but "pro-choice," and that they only advocate further research and education in the interest of children's safety. But others aren't so careful -- and there's enough misinformation out there to confuse any parent.

The nation's childhood immunization coverage is the highest it's ever been: 80 percent. Maryland's is 80 percent as well, and state health officials haven't seen an increase in requests for exemptions from required vaccinations.

Still, the vaccine anxiety has doctors worried. The last time it swelled up, there was a 10 percent dip in immunization levels, one factor that led to a nationwide measles epidemic between 1989 and 1991, according to the Centers for Disease Control and Prevention. In Maryland, 544 cases were reported and one out of five ended up in the hospital; nationwide, there were about 55,000 cases and 120 deaths.

The issue of vaccine safety is as old as the smallpox vaccine, developed in the 18th century. Because the vaccine was formed from the cowpox virus, "there were people concerned that the vaccine would turn them into cows," Halsey says.

"But even back then, there were some people who had very bad reactions to it. There are adverse reactions now, and I don't want to minimize their seriousness at all. But these are very rare."

A few recent headline-grabbing vaccine issues also served to shake some parents' trust in immunization: The CDC called on doctors to use the killed polio vaccine, because the live oral vaccine was linked to development of polio in 10 children. The DPT shot, believed to have caused adverse reactions, was replaced by the safer DtaP vaccine.

And two items came in July: The preservative thimerosal, used in many vaccines, has a trace of mercury, which, theoretically, might cause harm. The American Academy of Pediatrics recommended that doctors wait until children are a few months older before giving the Hepatitis B vaccine, and asked manufacturers to quit using thimerosal.

Then a vaccination program against rotavirus, an infection that causes infant dehydration and death, was suspended after reports that it might have harmed 20 children. The vaccine was taken off the market Oct. 15.

No one at the CDC or at any major medical institution denies that serious adverse reactions to vaccines do occur. The difficult part is separating an injury caused by a vaccine from a disorder that a child would fall prey to for any other reason.

If a child has an episode of uncontrollable crying, a sudden change in behavior, a seizure, a parent looks back to see what was different, what could have been a cause. Because young children have relatively frequent vaccinations -- about 22 by age six -- and because this might be the only medical visits a child needs, it's easy to assume that the disorder stems from the vaccination. And some conditions such as autism are usually diagnosed around the same age that a child is getting immunized, leading to another assumption that there was some connection.

But just because two things are related temporally doesn't mean they're related causally.

As the CDC puts it, "You might as well say that eating bread causes car crashes, since most drivers who crash their cars could probably be shown to have eaten bread within the past 24 hours."

"It's terrible when something happens to a child," Halsey says. "When something bad happens, we all look for a cause. We all can identify with that logic. It's human nature to want to find a cause -- but then we have to use good science to separate cause from chance."

To that end, the CDC and FDA established the Vaccine Adverse Event Reporting System, to collect reports of suspected vaccine reactions and create a database. This lets researchers identify trends, and makes danger points stand out.

Anyone can report a suspected problem to the vaccine reporting system -- you don't have to be a doctor. The system gets about 800 to 1,000 reports a month. About 85 percent of these are reports of fever or crying after a shot. Some vaccine opponents cite the number of reported problems as if these were proven adverse reactions, which causes confusion.

Others examining vaccines look at apparently rising levels of certain disorders, then look at the rising immunization coverage, and extrapolate that these are related -- that the vaccines somehow trigger autism, attention deficit disorder, chronic fatigue syndrome, or even teen violence.

"It's part of an overall problem -- somebody can make an allegation of any kind," Halsey says. "That allegation can be investigated, but it takes time to do the science."

J. Barthelow Classen, a physician and head of Classen Immunotherapies in Baltimore, says his research indicates a relationship between vaccination and the rise in diabetes cases. He believes that vaccines can stimulate diabetes, but also that vaccines early in life can help protect against diabetes.

"Vaccines are really based on junk science and that's what's coming back to haunt us," Classen says. He says they might have stopped disease, but that doesn't prove that people are healthier.

At an Institute for Vaccine Safety workshop, his data were presented, but other data demonstrated that diabetes has also risen in areas without new vaccine coverage. The workshop also presented data saying that in animals, some vaccines given in infancy can have a protective effect against diabetes.

Classen says that the CDC promotion of immunization is tainted by politics. "The president believes he can get more votes if he promotes immunization, and they carry out his political agenda."

The Clinton administration has set a goal of promoting 90 percent child immunization coverage. But individual states, not the federal government, decide immunization requirements. Nearly every administration this century, regardless of party, has promoted some sort of immunization initiative.

It's difficult to hash out scientific matters in the political arena, where every voter's viewpoint, regardless of knowledge or training, is equal.

But some groups with vaccine safety concerns have taken their cause to Washington, a common strategy for those with views outside the medical mainstream. A congressional hearing, for instance, can bring more attention to an issue than a medical report.

Others say concerned parents have a right and obligation to lobby, and representatives to provide a forum.

Ironically, it was parent lobbying in part that led states to set immunization requirements for schools in the 1970s. Today in Maryland, immunization is required for most day-care and school admissions.

Exemptions are allowed for those whose religious beliefs don't allow certain types of medical care, and for medical reasons -- for children with leukemia, for instance, or HIV infection.

So if these children can go unvaccinated, what would it matter if a few more, whose parents are worried about side effects, don't get their shots?

The answer is in a phenomenon called "herd immunity." When vaccine coverage increases in a population, it decreases the chances that those who aren't immunized will encounter the infection. Those who've had their shots protect those who can't get them. As the proportions shift, however, it makes it more likely that an epidemic can take hold.

Also, no vaccine is 100 percent effective (something that the CDC and other medical institutions admit freely). In any population, some people won't be protected even if they have had their shots. But these people can be protected by herd immunity as well, as long as the "herd" is big enough.

This is why anti-vaccine sentiment alarms the medical community. "All physicians who count children among their patients should be prepared more than ever to counsel parents about the facts of childhood vaccination," said an editorial in a recent American Medical News.

It also pointed to another troublesome area: "The Internet has given [the] contrariant movement what can best be described as a healthy shot in the arm."

With limited time and health plans that can restrict access to doctors, parents turn more often to the Internet and to various health books for medical advice. But what they find there can be confusing or misleading. On immunization, Web sites can range from the benign to the ridiculous -- and in between are many that can raise parents' emotions and fears.

As the debate and research continues, one thing is clear: Most everyone involved is motivated by the desire to keep children healthy.

As the American Medical News editorial sums up: "Still, better an epidemic of questions than the return of one that could claim the lives of children."

What are the risks?

* The risk of encephalitis or severe allergic reaction to the MMR (measles, mumps, rubella) vaccine is one in a million.

* The risk of encephalitis from measles is one in 2,000.

* The risk of encephalitis from mumps is 1 in 300.

* The risk of death from measles is 1 in 3,000.

* A pregnant woman who contracts rubella can have an 85 percent chance of having a child with congenital rubella syndrome: an array of birth defects or fetal death.

About diseases:

* Hepatitis B is not a disease limited to intravenous drug users. Children can contract hepatitis B in day-care or other situations through contact with another infected child. They can carry the infection for 20 to 30 years without symptoms, but later develop cirrhosis or liver cancer.

* Diphtheria causes a thick, coating membrane in the throat that can cause suffocation. The infection can be passed through blankets or clothing.

* Pertussis, or whooping cough, was formerly a major cause of child death and is particularly dangerous in infants.

* Mumps can make a man sterile. The disease can also damage the nervous system. An infected person can carry the disease without symptoms for as long as several months.

Cutting through the confusion

* Talk to your pediatrician. She is the best source of advice on your individual child's health.

* If you are concerned about vaccine reactions, ask your pediatrician about what a normal reaction after an immunization is and what might not be.

* Some health conditions merit delaying a scheduled vaccine. Ask your pediatrician.

* Keep track of immunization records so that vaccines can be given at the recommended times and amounts. The Maryland Health Department encourages physicians to check children's charts for immunization records every time a child comes to the doctor.

* Remember that anyone can put up a Web site or publish a book. Check references and credentials and cross-check information until you are satisfied that it's accurate.

* Call the National Immunization Hot Line: 800-232-0233 (English) and 800-232-0233 (Spanish.)

* Check the Centers for Disease Control and Prevention Web site for news, studies and comprehensive, easy-to-understand question-and-answer pages: www.cdc.gov

Sources: CDC, Maryland Health Department

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