More high school students are using condoms than 20 years ago, but progress has stalled with a lot of work still needed to protect young people from the AIDS virus, government researchers reported Tuesday. According to the Center for Disease Control, 4 of every 10 new HIV infections occur in people younger than 30. The teen years, just as youths become sexually active, are key for getting across the safe-sex message.

Using a long-standing survey of high school students' health, the CDC tracked how teen sexual behavior has changed over 20 years. About 60 percent of sexually active high school students say they used a condom the last time they had sex, researchers said Tuesday at the International AIDS Conference. That's an improvement from the 46 percent who were using condoms in 1991.

"This is good news," said Dr. Kevin Fenton, director of CDC's HIV prevention center. But, "we need to do a lot more."