After reviewing all 12,424 reports of adverse events after HPV immunization made to the joint CDC-FDA Vaccine Adverse Events Reporting system from June 2006 through December 2008, researchers from the two agencies reported that, generally, adverse event rates were similar to what is seen in safety reviews of other vaccines. However, they did acknowledge the presence of "disproportional reporting" of syncope (8.2 per 100,000 doses) and blood clots (0.2 per 100,000), compared with that seen with administration of other vaccines.
CDC, FDA Study Reinforces Safety, Efficacy of Gardasil
Report by American Academy of Family Physicians
True, but an incomplete statement. Most of the women who had problems with blood clots had other risk factors, the key one being that they were on oral birth control when they got the shots. I think that was probably another factor in recommending that girls get the shot BEFORE they become sexually active.