Happy Valentine's Day! To celebrate, the CDC got you a romantic little pair of studies that declare America to be in the midst of "an ongoing, severe STI epidemic." With 20 million new infections in 2008 (the most recent year studied in the reports) and 110 million ongoing infections, sexually transmitted infections cost the United States $16 billion in 2008, reports NBC News. Worst hit are people ages 15-24, who are about one-quarter of America's sexually experienced population but account for half of all STIs.
With the highest rate of STIs in the industrialized world, the United States' epidemic is led by HPV, with 14.1 million new infections in 2008 and 79.1 million ongoing. Chlamydia ranked second, with 2.9 million new infections. Sex researchers say the HPV problem is especially troubling considering the virus can trigger cervical, oral, anal, and penile cancers, and cause genital warts. Even though effective vaccines exist for HPV, only 35% of girls and 28% of boys ages 13 to 17 have been fully immunized—Australia's school vaccine program has 72% of girls vaccinated by age 15. "How could we possibly have done this to ourselves?" asks one public health official, saying that because of the lack of a comprehensive vaccine program, "we have snatched defeat from the jaws of victory." (Read more sexually transmitted diseases stories.)