Progress in getting teens to have safer sex largely has stalled over the last decade, a new CDC study suggests.

Nearly half of high school students (47%) have had sex, according to the 2011 Youth Risk Behavior Survey (YRBS). That's almost the same percentage reported in the 2001 survey -- 46%.

That means the decline in sexually active teens seen in the 1990s -- from a 1991 high of 54% -- is now stalled. So are other markers of safer sex (or abstinence) among teens:

    34% of high school students had sex in the preceding three months. There's been little decline since the 1990s saw a slight decline from 38% in 1991.
    15% of high school students had four or more sex partners, stable since 14% in 1991 but not as high as the 19% seen in 1991.
    60% of high school students used a condom the last time they had sex.

"We have to step back and think about the lack of urgency about the HIV/AIDS epidemic in the U.S.," Kevin Fenton, MD, director of the CDC's AIDS center, said at the International AIDS Conference. "Fewer Americans say HIV is a health concern. This influences the vigor and commitment that schools and communities have in providing sexual health information to children. ... We have to generate a new sense of urgency. Part of that will be getting back on track reducing HIV behavior in young people."

One bright point in the study findings is that the sexual risk behaviors of African-American teens are dropping to levels similar to those of white and Hispanic teens. In fact, African-American teens are even more likely than other teens to use condoms.

But rates of sexual initiation, multiple lifetime sex partners, and recent sex remain higher among African-American teens.

"Age at first intercourse has not changed since we have been tracking it," study leader Laura Kann, PhD, said at the AIDS conference. "It still is usually about age 16 for boys and for girls."

The YRBS survey includes a large national sample of high school students, who answer very personal questions anonymously and in private. Pregnancy and STD data suggest that kids tend to tell the truth on YRBS questionnaires.