By Liz Szabo, USA TODAY
Vaccines are one of the most controversial topics among parents these days, with a growing number questioning whether to give their kids recommended shots.
Nearly 40% of parents have delayed or declined at least one of their children's shots — a practice that's fueling outbreaks of infectious diseases, from mumps to measles and whooping cough, that were once nearly eliminated by vaccination, according to the Centers for Disease Control and Prevention.
Yet much of the anxiety about vaccines is based on myths and fear, rather than facts, say pediatrician Paul Offit and journalist Seth Mnookin, the authors of two new books that aim to clear up the confusion. Offit, chief of infectious disease at Children's Hospital of Philadelphia is author of Deadly Choices: How the Anti-Vaccine Movement Threatens Us All (Basic Books, $27.50). Mnookin is author of The Panic Virus: A True Story of Medicine, Science and Fear (Simon & Schuster, $26.99).
Myth 1: Vaccines cause autism
Few medical myths have been debunked as thoroughly as this one.
Fourteen scientific studies have failed to find a link between autism and vaccines, says Offit.
The myth was fueled by a small, flawed study in The Lancet in 1998, which was later retracted. British medical authorities last year found the author guilty of serious misconduct related to the study — including accepting more than $675,000 from a lawyer hoping to sue vaccine makers — and removed his ability to practice medicine in England.
Editors of BMJ, the British medical journal, have even called the study "an elaborate fraud," accusing author Andrew Wakefield of deliberately falsifying medical data.
Legal authorities, including a federal "vaccine court" handling the Omnibus Autism Proceeding, in which judges considered the claims of roughly 5,000 families, also have ruled against parents who claimed that shots caused their children's autism.
But myths, once unleashed, can be hard to rein in, says Mnookin.
"This idea has been set in people's minds, and it's going to take a while to overcome it," Mnookin says. "I talk to people who look at the research and say, 'I just don't trust it.' But for this to be a conspiracy, it would have to be virtually every government in the world."
Myth 2: Vaccines contain toxic chemicals
Over the past 200 years, critics have made claims that vaccines contain methyl mercury, ether and anti-freeze, as well as the blood and entrails of bats and toads, Offit reports in his book.
None of that is true.
Vaccines have never contained methyl mercury, a toxic metal that can cause brain damage, Offit says.
Before 2001, some vaccines contained thimerosal, a preservative made with ethyl mercury. But ethyl mercury, which is safe, is very different from methyl mercury, which is toxic.
While most laypeople don't pay attention to such differences, they're important, says obstetrician-gynecologist Jennifer Gunter, author of The Preemie Primer. Consider the huge difference between ethyl alcohol — or drinking alcohol, found in wine and beer — and methyl alcohol, or wood alcohol, which can cause blindness, she says
As proof of its safety, Offit notes that seven studies have failed to find any link between thimerosal and autism.
To address parents' concerns, however, the Food and Drug Administration ordered that thimerosal be removed from routine childhood vaccinations.
Today, thimerosal is found in only one type of shot: flu vaccine stored in multi-dose vials use the preservative to prevent the growth of fungus or other potentially dangerous germs, says Ari Brown, a spokeswoman for the American Academy of Pediatrics and author of Expecting 411.
Parents who remain concerned can ask for a thimerosal-free version, which is readily available. Neither flu shots in individual-dose containers or the FluMist nasal spray contains thimerosal, Brown says.
Some parents are also concerned about potential harm from aluminum, used in small amounts in some vaccines to stimulate a better immune response.
Yet babies get far more aluminum from food — including breast milk — than from vaccines.In the first six months of life, a breast-fed baby takes in 10 milligrams of aluminum; a baby given a milk-based formula takes in 30 milligrams; a soy formula-fed baby gets 120 milligrams, Offit says.
One teaspoon of Maalox liquid, an antacid, has 200 milligrams of aluminum, Gunter says.
In comparison, a baby who receives all recommended shots takes in only 4 milligrams of aluminum, Offit says.
Aluminum is also found in self-rising flour, Offit says. For most people, the biggest source of aluminum is cornbread.
And while many medications and consumer products have trace levels of chemicals, so do our bodies, Offit says. Young infants have 10 times as much formaldehyde circulating in their bodies than is found in any vaccine. Breast milk and infant formula both have more mercury than vaccines. But vaccines, like breast milk, play a vital role in keeping infants healthy.
"If you have zero tolerance for mercury, you have to move to another planet," Offit says. "We all have mercury and formaldehyde and aluminum in our bodies. Vaccines don't add to what we normally encounter every day."
Myth 3: Children receive too many vaccines, overwhelming their immune systems
Again, there's no sound evidence to support this, Offit says. Researchers have studied the question and found no increase in autism among kids who get multiple vaccines at an early age.
What many parents don't realize, he says, is that kids today get less of an immune challenge from their vaccines than their parents and grandparents did — even though kids today get more shots.
A century ago, kids were vaccinated against only smallpox.
Today, children are vaccinated against 14 diseases.
Yet today's shots contain fewer germ particles — the proteins that prime the immune system to respond to infections, Offit says.
That's because the vaccine against smallpox — the largest of the world's more than 1 million viruses — contained 200 germ particles, Offit says.
That's more antigens than are found in all 14 of today's shots combined, Offit says.
New shots also are engineered to be more targeted than earlier generations of vaccines, Brown says.
For example, whooping cough shots made before 1991 contained 3,000 different germ particles, or antigens. Today's version has only three to five, Brown says.
Experts note that the immune system is stronger than many realize.
When leaving the womb, babies are immediately surrounded by millions of bacteria in the birth canal. If the immune system weren't so robust, humans wouldn't survive being born, Offit says. People actually have 10 times more bacteria living on the surface of their bodies than human cells inside it.
Given that sort of daily challenge, the body's immune system has no trouble handling the few viral or bacterial proteins found in vaccines, Offit says. Even if children got 11 shots at once, they would still need only 0.1% of their immune system to respond.
Myth 4: It's safe to "space out" vaccinations
A growing number of parents are delaying vaccines to avoid giving their children several shots at once, sometimes because they're afraid of inflicting unnecessary pain.
But spacing out vaccines may actually cause children more distress, Offit says.
Studies show that a child's stress hormone levels peak after one shot. Because that one shot is so stressful, giving a child additional needle sticks doesn't appreciably increase a child's distress, he says. So children who receive one shot a month, instead of several at once, may actually have higher total stress levels.
Postponing shots also leaves babies at risk, Brown says.
The vaccination schedule developed by the CDC wasn't developed "out of thin air," Brown says. It's based on research to "protect as many babies as soon as possible."
The "nasty little truth" to alternative schedules, on the other hand, is that they "are all fantasy," Brown says. None of the alternative schedules has been clinically tested — the kind of evidence upon which the CDC relies.
"There is absolutely no research that says delaying certain shots is safer," Brown says. "Doctors who promote these schedules are simply guessing when to give which shots. What we know for certain is that delaying your child's shots is playing Russian roulette."
Myth 5: Vaccines cause lots of serious side effects
Vaccines are tested in more children — over a longer period of time — than any other drug, Offit says. Research overwhelmingly shows them to be safe.
The human papillomavirus (HPV) vaccine, for example, was tested in 30,000 women before being approved, Offit says. The pneumococcal vaccine was tested in 40,000 children. The two rotavirus vaccines were tested in a total of 130,000 children. All were tested for more than 20 years.
When introducing any new vaccine, the FDA also requires pharmaceutical companies to prove that their product doesn't pose a threat when added to the existing vaccine schedule, Offit says.
In addition, a special database, the Vaccine Adverse Event Reporting System (VAERS) helps scientists to monitor vaccine safety, Offit says. Anyone can use the system to report a suspected side effect.
Not everyone understands how to interpret this safety information, however.
Some parents looking at VAERS reports are alarmed by the large number of illnesses that occur after vaccinations. Offit says parents should remember that the database is a screening system, meant to cast as wide a net as possible in order to detect the greatest number of potential problems.
The system can't determine cause and effect, however.
A mother may report that her child had a seizure after getting a vaccine, for example.
But VAERS doesn't include a comparison group, showing how many children developed seizures after NOT getting a vaccine, Offit says.
In many cases, the side effects reported to VAERS are coincidences.
And 80% of people who reported to VAERS that vaccines caused autism were personal-injury lawyers, Offit says.
Vaccine makers often take a cautious approach when writing their warning labels, listing all of the side effects reported after vaccination — even if these side effects occurred at the same rate in unvaccinated people, Offit says.
Myth 6: Vaccine-preventable diseases aren't that dangerous
Vaccines are a victim of their own success, Mnookin says.
They have nearly eliminated diseases that once sickened, disabled or killed hundreds of thousands of Americans. But because few young parents have encountered any of these diseases, they don't realize how dangerous they are, Mnookin says.
Whooping cough, for example, once sickened 300,000 people a year and killed 7,000 — mostly young children, Offit says.
Now, partly because of failure to vaccinate, whooping cough is making a comeback.
In California alone, whooping cough has sickened at least 7,800 people — and killed 10 babies under 3 months old, according to the state health department.
Unvaccinated children returning from trips abroad also have started outbreaks of measles and mumps, infecting both their unvaccinated friends and neighbors, and newborns too young to have gotten their first shots. Unvaccinated kids and adults aren't just risking their own health, Offit says. They're also risking the health of vulnerable people around them, such as people with immune deficiencies caused by disease or cancer therapy, who are more likely to be hospitalized by the flu, chickenpox or other infections.
"We've reached a tipping point," Offit says. "Children are suffering and dying because some parents are more frightened by vaccines than by the diseases they prevent."
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