The controversy was ignited by Republican presidential hopeful Michele Bachmann, who claimed that the vaccine against human papillomavirus, which can cause cervical cancer, was a "very dangerous drug" that could lead to "mental retardation".
That claim immediately drew a barrage of criticism from the medical profession and even from Bachmann sympathisers on the right, forcing her to backtrack slightly. She told a conservative talkshow: "I have no idea. I am not a doctor, I'm not a scientist, I'm not a physician. All I was doing is reporting what this woman told me at the debate."
But doctors and scientists say that her remarks risk further reducing the already low take-up rates for the vaccine, as more parents will be convinced to reject the vaccine for their daughters.
Professor Gregory Zimet, co-leader of the cancer control programme at Indiana University, said of Bachmann's comments: "People will say there's no evidence for it and that is true, there is no evidence. But I would go further: Bachmann is absolutely wrong."