Republican presidential candidate Rep. Michele Bachmann on Tuesday questioned the safety of a vaccine used to protect girls from a sexually transmitted infection that can cause cervical cancer.

During an interview on NBC’s “Today” show, the Minnesota congresswoman referred to the vaccine as “what potentially could be a very dangerous drug” and recounted an exchange she had Monday night with a woman after the debate among GOP presidential candidates in Tampa. The debate included a sharp exchange between Bachmann and Gov. Rick Perry (Texas), who tried to mandate the vaccine in his state.

“I will tell you that I had a mother last night come up to me here in Tampa, Fla., after the debate and tell me that her little daughter took that vaccine, that injection, and she suffered from mental retardation thereafter,” Bachmann said.

“It can have very dangerous side effects. The mother was crying when she came up to me last night. I didn’t know who she was before the debate. This is a very real concern, and people have to draw their own conclusion,” she said.

Most public health authorities, however, say that Merck’s Gardasil and a similar vaccine that was subsequently approved are safe. On Tuesday the American Academy of Pediatrics challenged the suggestion the vaccine could cause mental retardation.

“The American Academy of Pediatrics would like to correct false statements made in the Republican presidential campaign that HPV vaccine is dangerous and can cause mental retardation,” O. Marion Burton, the academy’s president, said in a statement. “There is absolutely no scientific validity to this statement.”

“This is a life-saving vaccine that can protect girls from cervical cancer,” Burton said.

The vaccines have been “tested in thousands of people around the world,” according to the federal Centers for Disease Control and Prevention’s Web site. “These studies showed no serious side effects. Common, mild side effects included pain where the shot was given, fever, headache, and nausea. As with all vaccines, CDC and [the Food and Drug Administration] continue to monitor the safety of these vaccines very carefully.” Some girls who get vaccinated also faint, the CDC noted.

“The vaccine has been licensed for over five years. Over 35 million doses have been given in the United States, and the evidence is it’s safe and effective. There has been no pattern of serious side effects or dangers associated with the vaccine,” said Joseph Bocchini of Louisiana State University Health Sciences Center, who chairs the CDC’s Advisory Committee on Immunization Practices working group on the HPV vaccine.

“One of the things that’s really important to remember with the use of vaccines is when we give vaccines to large numbers of individuals events that follow the vaccine are not always caused by the vaccine. Someone who was going to develop a medical problem is going to develop that problem whether they get the vaccine or not,” Bocchini said in a telephone interview.

He noted that the National Academy of Sciences Institute of Medicine in August concluded there was no evidence the vaccine was associated with any serious health problems, including any neurological or cognitive problems. The only possible association was with severe allergic reaction in some rare cases, which can occur with any vaccine.

Some advocates and experts, however, said they are concerned that there is insufficient evidence about how long the protection will last, whether serious side effects will emerge in the future, and whether the reduction in infections will necessarily translate into fewer cases of cancer.

“There are unanswered questions about the safety of HPV vaccines, but the larger question is the risks vs. the benefits. HPV vaccines are effective in the short-term but we don’t know if they are effective in the long-term,” said Diana Zuckerman of the National Research Center for Women & Families, a Washington-based advocacy group.

“All vaccines have risks. Usually the risks are small and it seems that the risks of HPV vaccine are small (but they do exist),” she wrote in an e-mail. “As long as the benefits are substantial the risks are worth taking, but it is not clear what the benefits of HPV vaccine are for children unless they are also protected as older teens and adults.”

The vaccines protect against the human papillomavirus (HPV), the most common sexually transmitted infection. HPV causes genital warts and, in women, can lead to cervical cancer, which strikes about 10,000 American women a year and kills about 3,700.

After the FDA approved the vaccine in 2006 for girls as young as 9, medical authorities recommended that they receive it at age 11 or 12 to protect them before they became sexually active. Some critics worried that vaccinating children would send a subtle signal that their parents assumed they would become sexually active and that it would give youngsters a false sense of security.

Merck began an ambitious marketing campaign and lobbying push to persuade states to add the vaccine to the list of those required for children to attend school. But the company eventually abandoned the strategy in the face of an intense backlash from those who argued that the decision should be left to parents. Although many states considered such mandates, only Virginia and the District imposed one.