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Vaccine Safety

Kim Goodman's first child, grant, screamed all night after getting the measles-mumps-rubella (MMR) vaccine. Then her second child, Jack, had the rotavirus immunization  -- which was later recalled because it was thought to cause bowel obstruction in some cases. Now Goodman is wary about giving the new pneumococcal vaccine to her third child, 2-month-old James. "My husband and I aren't nearly as trusting this time around," she says. "I'm nervous about all these shots, though I do understand their importance  -- my dad had polio."

The Goodmans aren't alone in their unease about the growing number of baby shots doctors recommend. (With the addition last year of the pneumococcal vaccine, a child gets 23 doses of seven different vaccines before age 6  -- a single well-baby visit may now include as many as five shots.) In one national survey, one in four parents said they believe that too many vaccines can weaken a child's immune system. In a poll of pediatricians and family physicians, three out of four said that at least one parent had refused to allow a child to be immunized in the past year. Fueling fears are stories about possible links between vaccines and autism, brain damage, and juvenile diabetes.

"We're seeing a crisis of trust," says Barbara Loe Fisher, president of the National Vaccine Information Center, a vaccine-safety advocacy group. "For too long, doctors have simply dismissed parents' worries, saying, 'You have to immunize or you're a bad parent.'"

For all the anxiety, U.S. immunization rates remain high. In 2000, 76 percent of children between 19 and 35 months old were fully immunized, down 2 percent from the previous year. But even a small falloff concerns public-health experts. "Any drop in immunization rates only increases the chance of potentially deadly outbreaks of vaccine-preventable diseases," says Paul Offit, M.D., chief of infectious diseases at the Children's Hospital of Philadelphia and coauthor of Vaccines: What Every Parent Should Know. In Colorado, researchers analyzed health records from 1987 to 1998 and found that unvaccinated children were 22 times more likely to get measles and 6 times more likely to get whooping cough. Since no vaccine is 100 percent effective, kids who've been immunized are also vulnerable: Even when there's a very slight drop in vaccination rates, immunized children suffer a higher incidence of these infectious diseases.

The good news: Recent studies have examined the major concerns raised about vaccines, with reassuring results. At the same time, new steps have been taken to make vaccines safer and to identify the tiny subset of children  -- fewer than 1 in 10,000  -- who may be at risk of a significant reaction.

Contributing editor Jessica Snyder Sachs's most recent book is titled Corpse: Nature, Forensics, and the Struggle to Pinpoint Time of Death.

Small Shots, Big Fears

Recent research has debunked many fears that vaccines can cause certain childhood disorders:

  • Autism: In 1998 a British doctor urged a follow-up of his earlier observation that the MMR vaccine might, in rare cases, cause such behavioral problems as autism by triggering an intestinal disorder like Crohn's disease. He had based his conjecture on a small group of cases  -- 12 children. Since then, several large-scale investigations in the U.S., England, and Finland showed that neither Crohn's disease nor autism occurs more often following immunization.

  • Brain damage: In children 6 months to 5 years old, a fever can trigger brief seizures marked by jerking or stiffness. Two vaccines  -- the MMR and the diphtheria-tetanus-pertussis (DTP)  -- commonly cause fever and thus, in a small number of cases, seizures. These fever-related incidents occur in 1 in 3,000 children vaccinated against MMR and 1 in 1,700 kids inoculated with the old, whole-cell DTP vaccine. (The rate is markedly lower with the newer, "acellular" DTaP vaccine: 1 in 14,000 children.)

    In the vast majority of cases, convulsions caused by fever in young children do no lasting harm  -- although they can be frightening to parents. In about 1 in a million cases, though, these seizures are followed by epilepsy, coma, or mental impairment. In such instances, some researchers suspect, the fever simply unmasked an underlying condition: If the vaccine-related fever hadn't triggered the onset of the disorder, another fever would have done so. There hasn't been enough research to know for sure whether this is true, and in rare instances, seizures are not fever induced.

  • SIDS (sudden infant death syndrome): Anti-vaccine groups also claimed that whole-cell DTP increased the risk of SIDS, but large studies have found that immunized infants actually have a slightly lower risk.

  • Multiple sclerosis: In 1998 France suspended hepatitis B immunization requirements among children following isolated reports that tied the vaccine to multiple sclerosis. Soon afterward, drug companies funded several international studies, and no evidence was found to link the two.

  • Allergies: In the 1990s one hypothesis explaining the rise in the rates of allergic diseases, such as hay fever, asthma, and eczema, was that better hygiene was shielding children from the germs they needed to "educate" their immune system to distinguish harmless substances like pollen and dust from more harmful bacteria and viruses. Some scientists wondered whether vaccines might contribute to that by preventing kids from contracting "normal" childhood diseases. A recent study of immunization rates at 91 medical centers in 38 countries put such concerns to rest, showing no association between vaccination and the incidence of allergic diseases in children ages 6 to 7. In a separate study of children ages 13 to 14, those with the highest immunization rates actually had lower rates of allergic conditions.

  • Juvenile diabetes: In 1997 an immunologist theorized that the timing of the flu vaccine might have an influence on the occurrence of Type 1 diabetes. But a 2001 study done by the Centers for Disease Control and Prevention (CDC) that compared infants who developed diabetes with those who did not found no link between the time the vaccine was given and the disease.

  • Weakened immunity: One of the charges leveled most frequently by anti-vaccine activists is that too many immunizations can overwhelm a young child's developing immune system. This theory is currently being investigated by the Immunization Safety Review Committee, created by the CDC and the Institute of Medicine of the National Academies of Science. But pediatric immunologist Richard Johnston, M.D., at the University of Colorado School of Medicine says that taken together, the purified antigens (compounds that stimulate an immune response, which protects against the real disease) in all of the recommended childhood vaccines represent a mere drop in the ocean compared to what small children are exposed to in their daily lives. And many studies have found that when several vaccines are combined into one shot  -- standard practice  -- no major adverse side effects have been detected.

    Working Toward Safer Shots

    Even though scientists have dispelled many rumors surrounding the dangers of childhood inoculations, there are still risks. Some recent changes aim to reduce them:

    Three years ago, the American Academy of Pediatrics (AAP) advised pediatricians to stop using the oral polio vaccine (which causes actual polio in 1 in 2.4 million doses) as well as the whole-cell DTP vaccine (which can cause side effects like fever, convulsions, and, in rare cases, an extreme allergic reaction). Now, only inactivated polio vaccine is used. Doctors may still have the old, whole-cell DTP in stock, so ask for the DTaP one.

    Another concern has been mercury, which is used in small amounts as a preservative in vaccines. In 1999 the Food and Drug Administration (FDA) warned that with more baby shots, mercury levels in infants could rise above safe levels. Major public-health organizations and the pharmaceuticals industry agreed to remove the toxic metal from pediatric vaccines. All are now available in at least one mercury-free formulation, but you'll need to specifically request it.

    The biggest change occurred with the rotavirus vaccine, which protected against serious infant diarrhea. It was only on the market for a year when CDC studies showed that children with a rare form of bowel obstruction called intussusception were more likely to have received the vaccine the week before. The risk was very, very small  -- it didn't become apparent until 15 out of 1.5 million babies who received the shot got the condition. Researchers are now working on a new vaccine.

    Sharpening the Watchdog's Teeth

    While American vaccines are safe for the vast majority of kids, extremely rare side effects may still show up  -- after millions of children have been treated. "The challenge is to understand the one-in-ten-thousand or even one-in-a-million serious complication," says Robert Chen, M.D., chief of vaccine safety and development at the CDC's National Immunization Program. To do so, doctors must diligently report any troublesome reaction to the CDC. To improve safety, the CDC is creating a network of Clinical Immunization Safety Assessment centers, where doctors can refer patients who may have experienced an adverse reaction. The centers not only will allow physician-researchers to study these reactions more closely but will also foster the development of specialists qualified to understand them.

    Unfortunately, the CDC has funding to open only four such centers so far. Congress may be called upon to fund more by using a small portion of the $1.6 billion now deposited with the Vaccine Injury Compensation Program, derived from a 75-cent tax on every vaccine. "The result  -- more information on vaccine safety  -- would be a win-win situation," says Dr. Chen.

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