As Summer Estall approached her first birthday, her mom, Lisa, had more on her mind than party plans. Summer was about to receive not only cake and presents, but also -- surprise! -- her fourth round of shots in ten months. "Her last vaccinations had been tough," says Estall, of Grand Forks, North Dakota. "She was her usual happy self after being examined by the doctor, but then we were called into a room where two nurses were both holding long needles. They told me to lay Summer on the table, pull her pants down, and pin down her arms. Of course, she started to scream, and it felt like I was preparing her for torture. By the time the nurses got the Band-Aids on, Summer seemed to be okay -- but I was a wreck."
However, it wasn't just the painful pricks that worried Estall about her daughter's 12-month shots. "Everywhere I go, someone's talking about the danger of vaccines," she says. "There are moms posting about their kids' side effects on just about every online parenting forum. The other day I had coffee with two friends, and one of them said she wasn't vaccinating her kids. I can't help but wonder: Should I really be injecting a healthy child with these things?"
The answer from the vast majority of medical experts is a resounding "yes." The Centers for Disease Control and Prevention (CDC) and the American Academy of Pediatrics (AAP) recommend that healthy children get vaccinated against 14 diseases by age 2 (with boosters later for some), along with an annual inoculation against the flu. In fact, the government supports vaccines so strongly that any uninsured child can walk into a clinic and get his or her shots for free. "Immunizations are simply one of the greatest public-health achievements," says Mary Glodé, M.D., professor of pediatrics at the University of Colorado in Denver.
And yet, despite doctors' reassurances and mounting evidence that underscores the safety and value of vaccination, many educated, dedicated parents are still wary of vaccines -- or passionately opposed to them. Although the national immunization rate has remained stable over the past decade (76 percent of children ages 19 to 35 months were up-to-date on all of their shots in 2008), that's still short of the government's goal of 80 percent. In some pockets of the country, a rising number of parents are delaying shots for their kids or skipping certain ones altogether, citing religious or philosophical exemptions from state laws that require kids to be vaccinated in order to attend school. As a result, there have been recent outbreaks of serious diseases that vaccines had virtually wiped out in the U.S., including measles, mumps, pertussis (whooping cough), and haemophilus influenzae type b (Hib), which was once the most common cause of bacterial meningitis in kids under 5.
Infectious-disease specialists say these cases are due to a breakdown of what's known as "herd immunity." In order for a community to be fully protected against a disease, 80 to 90 percent of its population needs to have been vaccinated, says pediatrician Lance Rodewald, M.D., director of the Immunization Services Division of the CDC. Whenever coverage drops significantly below that level, a school, a church, or a neighborhood becomes susceptible to the disease. Babies who aren't old enough to get the shot yet are at the greatest risk of becoming sick.
Most of the recent measles outbreaks have been traced to individuals who visited a country where vaccine-preventable diseases still flourish. "The fact is, all of these diseases still exist -- some circulate in this country and others are only a plane ride away," says Dr. Rodewald. "They could easily become widespread again if more people refuse vaccines."The Big Fear
Ask parents what scares them most about the shots, and you'll likely get one answer: autism. Many people believe that the increased number of vaccines -- children now get twice as many as they did in 1980 and can receive up to 20 injections by their first birthday -- are to blame for the rise in kids with autism spectrum disorders (ASD). The idea first made headlines in 1998, when Andrew Wakefield, M.D., a British gastroenterologist, published a study of 12 children in The Lancet that linked the measles, mumps, and rubella (MMR) combination vaccine with intestinal problems that he believed led to autism. The following year, the AAP issued a warning about thimerosal, the mercury-containing preservative that was found in most vaccines. Though it didn't mention autism specifically, it suggested that the use of vaccines with thimerosal could theoretically push an infant's total exposure of mercury, a neurotoxin, above safe limits, and it recommended that the preservative be removed from shots. The vaccine-autism hypothesis was solidly in the mainstream by the time actress Jenny McCarthy went public with her belief that vaccines caused her son's autism, describing in heartbreaking detail how "the soul left his eyes" on a 2007 segment of the The Oprah Show. "It was enough to scare any mother," says Eileen Pike, of West Palm Beach, Florida, who has chosen to delay certain vaccines for her son, now 23 months.
However, at least seven large studies in major medical journals have now found no association between the MMR vaccine and ASD -- and this February, The Lancet officially retracted Dr. Wakefield's original paper. (Revelations that he had failed to disclose connections to lawyers involved in vaccine litigation also emerged.) In March, the U.S. Court of Federal Claims, Office of Special Masters, a group of judges appointed to handle cases of families who believe immunizations were responsible for their child's autism, ruled that thimerosal in vaccines does not increase the risk of the disorder. (In 2008, a federal judge did award compensation to the family of Hannah Poling, a child with mitochondrial disorder, a rare condition that can show symptoms of autism, which she was diagnosed with shortly after receiving five vaccines.) Several demographic analyses have also found that autism rates continued to rise even after thimerosal was removed from all vaccines except some flu shots.
So why are there so many stories of children developing autism shortly after immunizations -- not just in the media, but also in the Vaccine Adverse Event Reporting System, the federally cosponsored program that collects reports of suspected vaccine-related injury or illness? Experts believe that the association is almost certainly coincidental. Children get their first dose of the MMR vaccine at 12 to 15 months, the age at which autism symptoms typically become noticeable, says Paul Offit, M.D., director of the vaccine education center at Children's Hospital of Philadelphia and the author of Autism's False Profits: Bad Science, Risky Medicine, and the Search for a Cure. "It's the same reason why there are reports of SIDS deaths after DTaP (diphtheria, tetanus, and pertussis) immunizations," says Dr. Offit. "Infants start the DTaP vaccine between 2 and 6 months, which is the time they're also most likely to die from SIDS." In fact, some autism activists now believe that we should't even do more studies about a possible vaccine connection because they take attention and money away from important research that is investigating other potential causes of the disorder. "We have to move forward and be willing to accept what science tells us: Vaccines do not cause autism," says Alison Singer, president of the Autism Science Foundation and the mother of a child with autism.Weighing The Risks
That doesn't mean that vaccines aren't capable of causing adverse effects beyond a sore arm and a slight fever. In 1986, the government created the National Vaccine Injury Compensation Program to reimburse families whose children had serious side effects, and it has awarded nearly $2 billion on 2,398 claims. But most doctors say that the odds of experiencing a vaccine-related injury are greatly outweighed by the dangers of catching a vaccine-preventable disease. The measles vaccine, for instance, can cause a temporary reduction in platelets (which control bleeding after an injury) in 1 in 30,000 children, but 1 in 2,000 will die if they get measles itself. The DTaP vaccine can cause seizures or a temporary "shocklike" state in 1 in 14,000 people, and acute encephalitis (brain swelling) in 11 in 1 million. But the diseases it prevents -- diphtheria, tetanus, and pertussis -- are fatal in 1 in 20 cases, 1 in 10 cases, and 1 in 1,500 cases, respectively.
If the FDA determines that a vaccine poses a real risk to more than a tiny percentage of children, the agency won't let it be used. "Before a new vaccine is approved, it goes through a prospective, placebo-controlled trial involving tens of thousands of children," says Dr. Offit, who was a cocreator of RotaTeq, one of two current rotavirus gastroenteritis vaccines. Once a vaccine is in use, side-effect reports are analyzed by the Vaccine Safety Datalink, a program that collects patient information from managed-care organizations. In 2001, government scientists concluded that Wyeth's Rotashield, an earlier vaccine against rotavirus, could cause one extra case of bowel obstruction for every 10,000 babies who were immunized each year, and they halted its use in the U.S. Sometimes vaccines are pulled from shelves as a precaution: In 2007, certain lots of Merck's Hib vaccine were recalled after the company found bacteria on manufacturing equipment, even though the vaccines themselves tested negative for contamination.