positive for the cancer-causing HPV types". Therefore, for example, if a girl is positive for HPV 16 when she is inoculated with the vaccine at any age, she will not be protected against it later, Harper said, "That means it's a failure and those people are at risk for getting the HPV 16 and 18 cancers later". The only way to test for the presence of HPV is through a vaginal swab- which is inappropriate for young girls, she said. So what happens if the girls are vaccinated anyway, not knowing whether they were carrying the virus at the time of their inoculation?  "They will not be protected if they were positive for the virus at the time they are vaccinated," Harper said. That is why it is important to note that the vaccine has not been tested for efficacy (effectiveness) in younger girls, she said.  Instead the effectiveness was "bridged" from the older girls to the younger ones - meaning that Merck assumed that because it proved effective in the older girls, it also would be effective in the younger ones. So far more than 40 cases of Guillian-Barre syndrome - a dangerous immune disorder that causes tingling, numbness and even paralysis of the muscles have been reported in girls who have received the HPV vaccine in combination with the meningiitis vaccine.  Scientists already know that sometimes a vaccine can trigger the syndrome in a subject.  "With the HPV vaccine the number is higher than expected, and we don't