What's the truth about childhood vaccines? Are they an effective way to safeguard kids against a range of potentially deadly illnesses? Or do they cause autism and other medical problems? Keep clicking as Seth Mnookin, the author of "The Panic Virus: A True Story of Medicine, Science, and Fear," separates vaccine fact from fiction with his list of common misconceptions. It's information that just might save a life.

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Myth: Vaccines cause autism

In 1998, a British doctor named Andrew Wakefield published an article about a possible link between the measles-mumps-rubella (MMR) vaccine and autism. But that study has since been debunked, and Wakefield lost his medical license in the midst of allegations over professional misconduct. Other scientists have failed to replicate his findings, and dozens of studies involving millions of children have found no link between childhood vaccines and autism.

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Myth: Childhood vaccines contain mercury

Some standard childhood vaccines used to contain the mercury-containing preservative thimerosal - but Mnookin says that except for certain formulations of the flu vaccine, that is no longer true. What's more, numerous peer-reviewed medical studies have failed to demonstrate any association between the levels of thimerosal children used to receive in vaccines and any neurological or developmental disorder.

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Myth: There's no risk to not getting vaccinated

Many childhood diseases have all but disappeared in the U.S. in recent decades. In part, that's because vaccines are so effective. But it's a mistake to assume - as some parents do - that these diseases no longer pose much of a threat. Earlier this year, at least 10 children were hospitalized with measles after an unvaccinated child sparked an outbreak in Minnesota. In 2010, whooping cough (pertussis) claimed the lives of 10 infants in California.

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Myth: There's no harm in delaying vaccines

Vaccines work best at preventing potentially fatal illnesses when they are administered according to the schedule recommended by the American Academy of Pediatrics and other leading children's health organizations. The schedule is designed so that the youngest and most vulnerable children are protected. Delaying vaccines is a bit like buying a new car and then waiting a year to start wearing the seat belts.

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Myth: Doctors are paid to give vaccines

One of the most stubborn rumors regarding vaccines is that pediatricians earn bonuses for each shot they administer. Mnookin says that's simply not true.

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Myth: Vaccines get too much credit for preventing illness

Some people say improved sanitation and better living conditions explain the steep decline in the toll taken by communicable diseases. Improved sanitation does help explain the decline in illnesses that spread via contaminated food or water (like cholera and typhoid), But scientists say the decline in airborne infections like measles, chicken pox, and whooping cough (which spread via coughing and sneezing) is overwhelmingly the work of widespread vaccination.

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Myth: "Natural" immunity is best

Some vaccine critics claim that "natural" immunity lasts longer than the immunity that comes from being vaccinated. That's true, but only in some cases. Problem is, natural immunity comes from actually having a disease, and that's much more dangerous than getting a vaccine for the disease. To take one example, all the children affected by the recent outbreak of measles in Minnesota will now have natural immunity - but more than half of them had to be hospitalized as a result of their infections.

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Myth: Kids today are vaccinated against dozens of diseases

Between birth and age six, the standard vaccination schedule calls for children to get a total of 14 vaccines, including the one for influenza. That number is more than in previous decades (five in the 1960s, seven in the 1970s, nine in the 1980s, and 11 in 2000). But advances in vaccine technology mean kids receive a total vaccine "load" that is smaller today than a half-century ago.

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Myth: Vaccines overwhelm developing immune systems

Vaccines contain specific proteins (antigens) that stimulate the body to produce infection-fighting antibodies. And today's vaccines deliver fewer different types of antigens than previous generations of vaccines. There's simply no evidence that vaccines "overwhelm" the immune systems of young children.

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Myth: Vaccines are given according to a one-size-fits-all approach to public health

States exempt certain children from being vaccinated, including those who are immunocompromised as well as those with certain illnesses or allergies to specific vaccine ingredients. And Mnookin says 48 states allow parents not to vaccine their children for religious reasons. Since these exemptions mean some kids are going without vaccines, the key to keeping disease rates low is to make sure that as many children who are eligible for vaccines get them.

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