Concern over the safety of childhood vaccines grew to a crescendo in the years following a study in the late 90s that claimed a link between autism and certain needles.
Subsequent studies proved those fears largely unfounded, and medical professionals were relieved that the science was able to quell most parents' fears.
Now, however, doctors are worried that Oprah Winfrey's tacit endorsement of one of vaccination's biggest critics will give rise to a new round of vaccine hysteria.
Pediatric associations in Canada and the United States are worried that the actress and former Playboy bunny, Jenny McCarthy, will use a new deal with Oprah to promote her emotionally resonant vaccine-skeptical views, despite the fact that they are not scientifically backed.
Ms. McCarthy suggests her son's autism was caused by the measles, mumps and rubella vaccine he received when he was 15 months old and she, along with boyfriend Jim Carrey, is a spokesperson for the "green our vaccines" campaign, which alleges there are toxins in childhood vaccines.