The HPV vaccine, which has been available since June, is suddenly big news because Gov. Rick Perry is mandating it for girls entering the sixth grade in 2008.

You probably know about the controversy Perry's move has caused — some lawmakers in his own Republican Party have asked the governor to rescind the order, but he's standing firm — but you might need more facts about human papillomavirus (HPV), the country's most common sexually transmitted disease, and the new vaccine to fight it.

Here is some information to review before you talk to your child's physician.

Facts about HPV

•HPV is a group of viruses that includes more than 100 strains, more than 30 of which are sexually transmitted.

•About 20 million people are infected with HPV, and 50 percent of sexually active men and women acquire genital HPV infection at some point in their lives. By age 50, at least 80 percent of women will have acquired genital HPV infection. About 6.2 million Americans get a new genital HPV infection each year.

•Most HPV infections have no signs or symptoms. That means most infected people are unaware they carry HPV and can unknowingly transmit the virus to a sex partner.

•Every year in the U.S. about 10,000 women get cervical cancer, and 3,700 die from it. It is the second-leading cause of cancer deaths among women around the world.The only known cause of cervical cancer is HPV, and the research on how it causes the cancer is solidly established, said Dr. Paul Offit, director of the Vaccine Education Center at The Children's Hospital of Philadelphia. "The parts of the virus that cause the cervical cells to get cancer is well-defined," Offit said.

HPV is also linked to other rare cancers such as anal, vaginal and penile cancers, according to the Centers for Disease Control and Prevention.

How the vaccine works

•Gardasil, made by Merck, is the first vaccine to prevent cervical cancer, precancerous genital lesions and genital warts due to HPV.A second vaccine being developed by GlaxoSmithKline is in the final stages of clinical testing.

•The vaccine targets girls and women 13 to 26 years old but can also be given to girls as young as 9.

•What about boys? Why not vaccinate them? "Good question," said Offit. "Australia recommends (the vaccination) for boys and girls. It would make sense." Doctors in the United States are not licensed to give the vaccine to boys, but research is under way that could lead to this.

•Gardasil prevents a vaccinated person from contracting (and thus transmitting) four of the more than 100 strains of HPV. Those four strains cause up to 70 percent of all cervical cancers and 90 percent of genital warts."Basically, it decreases your chances of getting cervical cancer by 70 percent,"said Offit. But this is only if a woman gets the vaccine before she's sexually active or has an HPV infection.

•The vaccine is most effective before first sexual contact. However, most sexually active women will still benefit from the vaccine, according to the Centers for Disease Control and Prevention. For example, a woman might have a certain strain of HPV, but the vaccine could prevent her from getting another.

•The vaccine does not treat existing HPV infections.

•The vaccine works by stimulating an immune response that protects against infection, without actually causing infection. It is not a live virus. Like the hepatitis B vaccine, the HPV vaccine is made with a single protein from the virus. That purified single protein, called L1, induces protective antibodies. Thus, the virus never gets to cervical cells.

Safety and effectiveness

•Gardasil is safe, according to the Advisory Committee of Immunization Practices, a panel of 15 experts in the immunization field who make recommendations to the CDC. "The crowning achievements of medicine in the 20th century are immunizations," said Dr. Walter Kuhl, a 24-year pediatrician with Austin Regional Clinic. "And if the FDA approves a vaccine, I believe it's safe."

•Because clinical trials have been going on for only five years, how do we know Gardasil is preventing cervical cancers? Doesn't it take longer than five years for cancer to develop? "Studies didn't show it prevented cancer but it prevented cervical changes that precede cancer. It takes about 20 years for cancer to develop," said Offit.

Offit doesn't get why parents would oppose the vaccine. "It's a no-brainer," he said. "The vaccine doesn't cause a disease. It prevents cervical cancer and has little or no side effects. Frankly, it's the best vaccine we have.

"From a parent's standpoint, the question is, 'Is it safe and effective for my child?' The answer is yes."

Getting the shot

•The series of three injections ($120 apiece) are given over six months. Kuhl, however, said the shots can be extended over a year.

•Kuhl said he's found most insurance carriers cover the vaccine. Coverage might vary, according to your carrier.

According to the Texas Department of State Health Services, more than 3,300 providers statewide have signed on to provide the vaccine free of charge through the Texas Vaccines for Children program. The federally funded program serves children 18 and younger who are eligible for Medicaid, uninsured, underinsured, American Indian or Alaskan Native. The shots will be available in early April through the Austin/Travis County Health and Human Services Department (972-5524).

•If you're worried about pain or anxiety for your child, the syringe used is comparable in size to syringes used with other vaccines.

•The vaccine has few side effects. Pain, redness, itching and swelling may occur at the injection site. Mild to moderate fever (100 degrees to 102 degrees) is also possible.

After vaccination

•"Sexually active women still need yearly pap smears to screen for cervical cancer," said Helen Hunter, a spokeswoman for the Centers for Disease Control and Prevention. That is because the vaccine doesn't protect against all strains of HPV that cause cervical cancer.

•The length of protection (immunity) is usually not known when a vaccine is first introduced. So far, studies have followed women for five years and found that they are still protected. More research is being done to find out how long protection will last, and whether a booster dose of vaccine will be needed.

Kuhl is aware of some parents' uneasiness about the vaccine. "One of the things I hear from parents is that they want to wait until the vaccine has been out a year or two," he said, "but I'm a proponent of it."

rgandara@statesman.com; 445-3632

Learn more about HPV

Visit the Centers for Disease Control and Prevention Web site (www.cdc.gov/std/HPV/STDFact-HPV.htm), the American Academy of Pediatrics (www.aap.org) or The Children's Hospital of Philadelphia (www.chop.edu; search for Vaccine Education Center).

Two parents, two views

Austinite Julie Drenner of Austin is the mother of four children, including girls ages 2 and 5. She's also Austin media liaison for the Dallas-based Texas Eagle Forum, a conservative group that strongly opposes the vaccine for young girls. She thinks girls will believe that the vaccine will protect them frompregnancy. As a board member of the nonprofit Austin Pregnancy Resource Center, she says she's seen the naiveté of girls. "I've seen a 14-year-old become a mother, and met other girls who believe that a single birth control pill will protect them for a long time," she said.

Another Austin mom, Sherry Varnado, whose daughter is in middle school, disagreed that the vaccine will give girls the license to become sexually active. "Kids at 11 only know they're getting a shot. That's it. If you want to get into the sex issue, that's a parent's job. You have to educate your children. It's basically how you raise your kids," she said.