By Sharon Cotliar
February 22, 2010 12:00 PM

In 1998 British physician Dr. Andrew Wakefield published a study on the possible link between autism and the measles-mumps-rubella (MMR) shot, setting in motion an anti-vaccine movement. Why has Wakefield been discredited?

A medical review board ruled that Wakefield displayed “callous disregard” for patients by taking blood samples at a birthday party, falsified data and failed to disclose funding sources. (Wakefield has denied the allegations.)

So, can vaccines trigger autism?

No, says Dr. Susan Levy, director of the Regional Autism Center at Children’s Hospital of Philadelphia. While researchers have yet to pinpoint why one in 110 children is now diagnosed with an autism spectrum disorder, Dr. Levy says, “Based on multiple studies, I’m very comfortable with the conclusion that vaccines do not cause autism.” For parents like Suzanne Chiang, who recently took son Daniel, 4, for his second MMR shot, the study’s retraction is “a big relief.” But not all parents are convinced: “I’m not going to vaccinate,” says Jason Peloquin of Brooklyn, who has a 19-month-old son and 4-month-old daughter. “I just feel there’s a correlation.”

Some Hollywood parents have been outspoken about this. What do they say now?

Jenny McCarthy, whose son Evan, 7, was diagnosed with autism around age 3, said in a statement that Wakefield is the victim of a “smear campaign” and that “over-vaccination of young children is leading to neurological damage, including autism.” Holly Robinson Peete, whose son RJ, 12, has autism, told PEOPLE, “There’s a lot of fear out there” over vaccines and called for “respectful conversations between pediatricians and parents.”

Does spreading out vaccines reduce the risk of autism?

No, experts say. In fact, the drop in vaccination rates resulting from parents delaying or declining vaccines has played a role in recent mumps and measles outbreaks around the country. The practice, says Dr. Levy, “puts the child and the people around them at risk.”