An FDA advisory panel will meet Wednesday to decide whether to recommend approval of that vaccine, called Cervarix, in females ages 10 to 25.
Cervarix targets two HPV strains, HPV 16 and HPV 18, which are leading causes of cervical cancer. It also contains an adjuvant, which is designed to enhance the immune system's response against those HPV strains.
HPV infection is common; the virus is sexually transmitted. Most women who get infected don't develop cervical cancer, and there are other possible causes of cervical cancer.
On its web site, the FDA states that Cervarix has been shown to be effective at preventing cervical cancer associated with HPV 16 and HPV 18 in teens and women up to age 25 who hadn't been exposed to those HPV strains.
In the vaccine's clinical trials, participants got three doses of Cervarix or a placebo over six months. Both groups had similar rates of serious adverse events or death, the FDA notes. "No patterns indicating a potential safety signal were discernible among the serious adverse outcomes," the FDA states.
However, the FDA has asked for a pregnancy registry to track miscarriage in women who get Cervarix around the time of conception, due to an "imbalance" in the proportion of those women who miscarried.
There is no proof that those miscarriages were due to the vaccine. Some of those miscarriages took place in countries where abortion is illegal, and the FDA notes that it's not clear if those were actually elective abortions that were reported as miscarriage.
The FDA also wants post-marketing studies to track any cases of autoimmune diseases (such as multiple sclerosis) and musculoskeletal conditions (including arthritis and fibromyalgia) in patients who get Cervarix. Again, there is no proof showing the vaccine caused rare cases of those conditions in clinical trial participants.
After the FDA advisory panel makes its recommendations, it's up to the FDA to make the final decision on whether to approve Cervarix. The FDA often follows the recommendations of its advisory panels but is not required to do so.
Cervarix and Gardasil are both given by a series of three shots spread over six months. No head-to-head studies have been done comparing the effectiveness of Cervarix and Gardasil.