Most are between the ages of 15 and 24.
HPV causes cervical cancer.
As Nanette Miranda reports, some doctors advocate for a mandatory vaccine to fight it.
It's a controversial proposal many states are grappling with: whether to make the HPV vaccine mandatory for girls before entering sixth grade.
It helps protect against four strains that cause nearly 70% of cervical cancer and is most effective if administered before the girl is sexually active.
Shaundra Hall survived the painful and emotional disease.
She said, "there is no reason why any woman should have to go through this any more with this vaccine that's been made available."
Some California lawmakers tried and failed twice to mandate HPV vaccines.
The concerns were that it's too new to know any of the long-term consequences and it forces parents to discuss the sexually transmitted virus to daughters as young as nine years old.
So the medical profession and public health workers met in Sacramento to discuss how to get more California girls vaccinated.
Dr. Dean Blumberg said, "It's a terrible disease to live through, and some people die from it. So if parents want their children to be protected agains cancer, they should have their children get this vaccine."
Maya Mathur did her own study among 200 Bay Area pre-teen and high school girls.
She found education might get more participation.
The high school senior herself got the vaccine but didn't know the importance of it.
She added, "The doctor just said I'm going to give you the HPV vaccine. Here's a fact sheet about it, and he gave it to me. My parents were involved in the decision, but I wasn't."
The other hurdle is cost.
It's $120 per dose, given three separate times over six months, and not all health plans cover it.
There has been some concern about side effects from the HPV vaccine, with at least one family claiming their girl may have died from it.
But the CDC just completed a study of all those accusations, and gave the vaccine its full blessing.
Virginia is the only state so far to mandate HPV vaccine for girls entering 6th grade.